<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:12e0c352-a34a-4028-838a-49983e76963a,g:6727717e-0ebc-4989-b0cc-f72f478bc692-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://soterahealth.com/role/ConsolidatedStatementsofOperationsandComprehensiveIncomeLoss" xlink:type="simple" xlink:href="shc-20241231.xsd#ConsolidatedStatementsofOperationsandComprehensiveIncomeLoss"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/ConsolidatedStatementsofOperationsandComprehensiveIncomeLoss" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_39d90ac3-5d8e-4e74-b1da-1d7708110418" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_StatementTable_39d90ac3-5d8e-4e74-b1da-1d7708110418" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_940fa8c2-0163-4531-ab0d-a8688b84fcae" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_39d90ac3-5d8e-4e74-b1da-1d7708110418" xlink:to="loc_srt_ProductOrServiceAxis_940fa8c2-0163-4531-ab0d-a8688b84fcae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_940fa8c2-0163-4531-ab0d-a8688b84fcae_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_940fa8c2-0163-4531-ab0d-a8688b84fcae" xlink:to="loc_srt_ProductsAndServicesDomain_940fa8c2-0163-4531-ab0d-a8688b84fcae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_c5d14e85-61e0-48f4-87d0-4685f42a8780" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_940fa8c2-0163-4531-ab0d-a8688b84fcae" xlink:to="loc_srt_ProductsAndServicesDomain_c5d14e85-61e0-48f4-87d0-4685f42a8780" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_54e7a0fa-9336-42db-8a01-571563cc38ce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_c5d14e85-61e0-48f4-87d0-4685f42a8780" xlink:to="loc_us-gaap_ServiceMember_54e7a0fa-9336-42db-8a01-571563cc38ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_98e3ea1c-4309-43cd-93d6-17086e99af3e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_c5d14e85-61e0-48f4-87d0-4685f42a8780" xlink:to="loc_us-gaap_ProductMember_98e3ea1c-4309-43cd-93d6-17086e99af3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_d372b810-90c5-420b-aae1-339f8e8f3270" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_39d90ac3-5d8e-4e74-b1da-1d7708110418" xlink:to="loc_srt_LitigationCaseAxis_d372b810-90c5-420b-aae1-339f8e8f3270" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_d372b810-90c5-420b-aae1-339f8e8f3270_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_d372b810-90c5-420b-aae1-339f8e8f3270" xlink:to="loc_srt_LitigationCaseTypeDomain_d372b810-90c5-420b-aae1-339f8e8f3270_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_ef3d7f6e-8477-447f-a7b5-0a1668c19c84" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_d372b810-90c5-420b-aae1-339f8e8f3270" xlink:to="loc_srt_LitigationCaseTypeDomain_ef3d7f6e-8477-447f-a7b5-0a1668c19c84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationGeorgiaMember_d02ada84-c233-4dc1-aa07-fcea9213da94" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationGeorgiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_ef3d7f6e-8477-447f-a7b5-0a1668c19c84" xlink:to="loc_shc_EthyleneOxideTortLitigationGeorgiaMember_d02ada84-c233-4dc1-aa07-fcea9213da94" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationIllinoisMember_be824522-d26a-4587-9814-8cc000c22121" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationIllinoisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_ef3d7f6e-8477-447f-a7b5-0a1668c19c84" xlink:to="loc_shc_EthyleneOxideTortLitigationIllinoisMember_be824522-d26a-4587-9814-8cc000c22121" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_0d9dc99c-2b53-4ae3-b396-3754dbc95782" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_RevenuesAbstract_0d9dc99c-2b53-4ae3-b396-3754dbc95782" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_d0a7de78-a5dd-4e01-9795-05abb86a3c4b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_0d9dc99c-2b53-4ae3-b396-3754dbc95782" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_d0a7de78-a5dd-4e01-9795-05abb86a3c4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenueAbstract_a8cb05b8-d8f7-4b5a-aa10-fd97e4e7c0ec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostOfRevenueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_CostOfRevenueAbstract_a8cb05b8-d8f7-4b5a-aa10-fd97e4e7c0ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_44bf41c4-e53b-4a92-a041-19bdd8443947" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostOfRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostOfRevenueAbstract_a8cb05b8-d8f7-4b5a-aa10-fd97e4e7c0ec" xlink:to="loc_us-gaap_CostOfRevenue_44bf41c4-e53b-4a92-a041-19bdd8443947" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_b0d4336e-d338-4464-a7aa-d8c0e3d779b8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_GrossProfit_b0d4336e-d338-4464-a7aa-d8c0e3d779b8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_45163742-d7d6-491b-a742-9b2a30931ba5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_OperatingExpensesAbstract_45163742-d7d6-491b-a742-9b2a30931ba5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_88ae9957-a18a-4b3d-ab21-0187da469af5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_45163742-d7d6-491b-a742-9b2a30931ba5" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_88ae9957-a18a-4b3d-ab21-0187da469af5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_AmortizationOfIntangibleAssetsNonproduction_fe7ca5e2-2370-446d-9eac-1faf412c9949" xlink:href="shc-20241231.xsd#shc_AmortizationOfIntangibleAssetsNonproduction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_45163742-d7d6-491b-a742-9b2a30931ba5" xlink:to="loc_shc_AmortizationOfIntangibleAssetsNonproduction_fe7ca5e2-2370-446d-9eac-1faf412c9949" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_ba836de2-8fd7-4bf1-bb3d-39b625ad750b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_45163742-d7d6-491b-a742-9b2a30931ba5" xlink:to="loc_us-gaap_OperatingExpenses_ba836de2-8fd7-4bf1-bb3d-39b625ad750b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_388d1404-ff2c-4d82-9ffd-d51cd90ad914" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_OperatingIncomeLoss_388d1404-ff2c-4d82-9ffd-d51cd90ad914" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_577ed1f6-9c8d-4373-b4d1-4f6920bcfa27" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_577ed1f6-9c8d-4373-b4d1-4f6920bcfa27" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_GainLossOnRefinancingOfDebt_69fef00d-6e08-4d21-9b8d-00332b28d688" xlink:href="shc-20241231.xsd#shc_GainLossOnRefinancingOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_shc_GainLossOnRefinancingOfDebt_69fef00d-6e08-4d21-9b8d-00332b28d688" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LitigationSettlementNonoperatingExpense_5c53bef0-82fe-4c53-947e-4b4cb70b1398" xlink:href="shc-20241231.xsd#shc_LitigationSettlementNonoperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_shc_LitigationSettlementNonoperatingExpense_5c53bef0-82fe-4c53-947e-4b4cb70b1398" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_ba2fdcb7-935f-46ef-ba72-3cfc2d5a6bd8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_ba2fdcb7-935f-46ef-ba72-3cfc2d5a6bd8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_f355e44b-8885-4397-982f-c57838a2f336" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_f355e44b-8885-4397-982f-c57838a2f336" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_ec499e60-52de-4d29-ad12-275ca3bbbf25" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_ec499e60-52de-4d29-ad12-275ca3bbbf25" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_2f20bad0-6922-412d-9984-a40a52156cec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_2f20bad0-6922-412d-9984-a40a52156cec" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_a2eaa8f3-74b9-4716-ae0b-a70cdfbeb2f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_a2eaa8f3-74b9-4716-ae0b-a70cdfbeb2f3" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_4167b4d2-4a70-4311-b3fe-d71d8b63b265" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_NetIncomeLoss_4167b4d2-4a70-4311-b3fe-d71d8b63b265" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_5921e8d8-4bc1-4063-ba44-ca2838592937" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_5921e8d8-4bc1-4063-ba44-ca2838592937" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_67547043-5cd2-41c9-8bbc-212c6a386897" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_5921e8d8-4bc1-4063-ba44-ca2838592937" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_67547043-5cd2-41c9-8bbc-212c6a386897" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax_ac2f0f25-ef6d-4c80-8140-fea897463bc8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_5921e8d8-4bc1-4063-ba44-ca2838592937" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax_ac2f0f25-ef6d-4c80-8140-fea897463bc8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_8728d642-bece-428a-890e-a6ecc728ceb9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_5921e8d8-4bc1-4063-ba44-ca2838592937" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_8728d642-bece-428a-890e-a6ecc728ceb9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_63c86908-1a3a-4c88-a4f2-49b5934b8ce3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_63c86908-1a3a-4c88-a4f2-49b5934b8ce3" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_aeb19122-a228-468c-bb35-9000fa6a9039" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_us-gaap_EarningsPerShareAbstract_aeb19122-a228-468c-bb35-9000fa6a9039" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_351db4a5-0077-419a-8195-ac177c751316" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_aeb19122-a228-468c-bb35-9000fa6a9039" xlink:to="loc_us-gaap_EarningsPerShareBasic_351db4a5-0077-419a-8195-ac177c751316" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_ae840331-aaa9-47cf-92b3-b3234d49fb2a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_aeb19122-a228-468c-bb35-9000fa6a9039" xlink:to="loc_us-gaap_EarningsPerShareDiluted_ae840331-aaa9-47cf-92b3-b3234d49fb2a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_WeightedAverageNumberOfSharesOutstanding1Abstract_1b44fb0c-dcbb-41eb-a302-072d85ba3f35" xlink:href="shc-20241231.xsd#shc_WeightedAverageNumberOfSharesOutstanding1Abstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2de516bb-0236-4c48-add2-dd933fb91141" xlink:to="loc_shc_WeightedAverageNumberOfSharesOutstanding1Abstract_1b44fb0c-dcbb-41eb-a302-072d85ba3f35" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_631cb50d-9382-4764-8746-2e381ae9596b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_WeightedAverageNumberOfSharesOutstanding1Abstract_1b44fb0c-dcbb-41eb-a302-072d85ba3f35" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_631cb50d-9382-4764-8746-2e381ae9596b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_4594e7eb-e425-44a7-be1f-a6aa597ac152" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_WeightedAverageNumberOfSharesOutstanding1Abstract_1b44fb0c-dcbb-41eb-a302-072d85ba3f35" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_4594e7eb-e425-44a7-be1f-a6aa597ac152" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/ConsolidatedStatementsofCashFlows" xlink:type="simple" xlink:href="shc-20241231.xsd#ConsolidatedStatementsofCashFlows"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/ConsolidatedStatementsofCashFlows" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_047688f7-8b27-41d8-b2a9-5e5d2b7085e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_db7fdcc0-9d47-4b4b-b7bd-3901e618b406" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_047688f7-8b27-41d8-b2a9-5e5d2b7085e1" xlink:to="loc_us-gaap_StatementTable_db7fdcc0-9d47-4b4b-b7bd-3901e618b406" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_f05b6940-1fd1-49dd-90e4-75ea5a683dc8" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_db7fdcc0-9d47-4b4b-b7bd-3901e618b406" xlink:to="loc_srt_LitigationCaseAxis_f05b6940-1fd1-49dd-90e4-75ea5a683dc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_f05b6940-1fd1-49dd-90e4-75ea5a683dc8_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_f05b6940-1fd1-49dd-90e4-75ea5a683dc8" xlink:to="loc_srt_LitigationCaseTypeDomain_f05b6940-1fd1-49dd-90e4-75ea5a683dc8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_559c13ed-e83a-4257-aeba-c5a9d033fc2b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_f05b6940-1fd1-49dd-90e4-75ea5a683dc8" xlink:to="loc_srt_LitigationCaseTypeDomain_559c13ed-e83a-4257-aeba-c5a9d033fc2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationIllinoisMember_9aaaecc9-e9a2-401e-8da0-e4f04d9d3ad3" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationIllinoisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_559c13ed-e83a-4257-aeba-c5a9d033fc2b" xlink:to="loc_shc_EthyleneOxideTortLitigationIllinoisMember_9aaaecc9-e9a2-401e-8da0-e4f04d9d3ad3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationGeorgiaMember_cd8be5e5-2d58-42b4-bce8-d812b3493d24" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationGeorgiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_559c13ed-e83a-4257-aeba-c5a9d033fc2b" xlink:to="loc_shc_EthyleneOxideTortLitigationGeorgiaMember_cd8be5e5-2d58-42b4-bce8-d812b3493d24" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_e1a85367-9871-490d-8185-1c8e6821d543" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_047688f7-8b27-41d8-b2a9-5e5d2b7085e1" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_e1a85367-9871-490d-8185-1c8e6821d543" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_0c0e76ca-d107-4dda-bce5-b3b91c81f814" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_e1a85367-9871-490d-8185-1c8e6821d543" xlink:to="loc_us-gaap_NetIncomeLoss_0c0e76ca-d107-4dda-bce5-b3b91c81f814" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_e1a85367-9871-490d-8185-1c8e6821d543" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_7cf74545-69dd-453a-898c-5023a71ec3c9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_Depreciation_7cf74545-69dd-453a-898c-5023a71ec3c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_f09b9e7d-e342-479b-8f59-86c758e2a76d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_f09b9e7d-e342-479b-8f59-86c758e2a76d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_GainLossOnRefinancingOfDebt_837e9439-93da-4058-a8d0-ac94e96fb265" xlink:href="shc-20241231.xsd#shc_GainLossOnRefinancingOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_shc_GainLossOnRefinancingOfDebt_837e9439-93da-4058-a8d0-ac94e96fb265" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_924604f2-6ec8-4cac-8456-d9971f54bb40" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_924604f2-6ec8-4cac-8456-d9971f54bb40" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_3b64167c-69da-4a63-be0e-53f084d8e394" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_3b64167c-69da-4a63-be0e-53f084d8e394" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_80b72a16-6d0d-40f1-93b6-246352ba50b7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_ShareBasedCompensation_80b72a16-6d0d-40f1-93b6-246352ba50b7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationAccretionExpense_3999b6b1-0361-421d-9969-c1277a0d2860" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetRetirementObligationAccretionExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_AssetRetirementObligationAccretionExpense_3999b6b1-0361-421d-9969-c1277a0d2860" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_66e8e745-0aec-4f36-bd97-6e5beec3024b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_66e8e745-0aec-4f36-bd97-6e5beec3024b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_c707e7c6-dc82-491e-ad90-0481c0e60a83" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_c707e7c6-dc82-491e-ad90-0481c0e60a83" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_93556c8d-985a-4d4d-bdba-11cd2cd139fe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_93556c8d-985a-4d4d-bdba-11cd2cd139fe" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense_583c7d65-a086-45e6-b46b-ffe4993b01a7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherNoncashIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_OtherNoncashIncomeExpense_583c7d65-a086-45e6-b46b-ffe4993b01a7" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_fcf9452b-6a6d-48e8-aab3-a9fa7ca8ad6b" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_d739c368-fe66-491c-99b1-121c80d00bec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_d739c368-fe66-491c-99b1-121c80d00bec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_edf38037-d98a-4fb9-802c-e74abfeaf2d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_edf38037-d98a-4fb9-802c-e74abfeaf2d7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherCurrentAssets_6c18e183-0ec9-4288-a4bd-1693084f6bdc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOtherCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherCurrentAssets_6c18e183-0ec9-4288-a4bd-1693084f6bdc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable_68fae87d-4a71-4964-a075-32c654b7e69d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayable_68fae87d-4a71-4964-a075-32c654b7e69d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_7e21426d-bde7-4710-9a63-dad317657950" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_7e21426d-bde7-4710-9a63-dad317657950" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossRelatedToLitigationSettlement_cee8f741-8075-4eb9-9a37-43526812a60f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainLossRelatedToLitigationSettlement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:to="loc_us-gaap_GainLossRelatedToLitigationSettlement_cee8f741-8075-4eb9-9a37-43526812a60f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_f62269da-d8ee-428b-ac42-1fc52991dcf4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_f62269da-d8ee-428b-ac42-1fc52991dcf4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_5986b18a-4fd7-45d4-9c71-ac65fb938d64" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_5986b18a-4fd7-45d4-9c71-ac65fb938d64" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_774acebb-ed9f-41af-aa39-2e0c12db062a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_65387365-0e84-419e-b8d5-4e170d20771d" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_774acebb-ed9f-41af-aa39-2e0c12db062a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_98f21451-8074-4b20-922b-febb05414fa4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_e1a85367-9871-490d-8185-1c8e6821d543" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_98f21451-8074-4b20-922b-febb05414fa4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_38325ceb-efe6-44d3-938f-239d9de33eee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_047688f7-8b27-41d8-b2a9-5e5d2b7085e1" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_38325ceb-efe6-44d3-938f-239d9de33eee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_468d4486-b845-43de-b95a-93a872ab21f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_38325ceb-efe6-44d3-938f-239d9de33eee" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_468d4486-b845-43de-b95a-93a872ab21f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAcquiredInExcessOfPaymentsToAcquireBusiness_59378f75-6287-49ea-a7f2-671894b73c19" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAcquiredInExcessOfPaymentsToAcquireBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_38325ceb-efe6-44d3-938f-239d9de33eee" xlink:to="loc_us-gaap_CashAcquiredInExcessOfPaymentsToAcquireBusiness_59378f75-6287-49ea-a7f2-671894b73c19" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_2e35e343-47d5-47ec-9156-415f6b09dca0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsForProceedsFromOtherInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_38325ceb-efe6-44d3-938f-239d9de33eee" xlink:to="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_2e35e343-47d5-47ec-9156-415f6b09dca0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_ec75bb6d-9480-4ade-a19b-bd4b43ec6d44" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_38325ceb-efe6-44d3-938f-239d9de33eee" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_ec75bb6d-9480-4ade-a19b-bd4b43ec6d44" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_466a380c-a377-4bd1-aa0a-20d33c94a710" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_047688f7-8b27-41d8-b2a9-5e5d2b7085e1" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_466a380c-a377-4bd1-aa0a-20d33c94a710" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_e0b4a57b-e212-44d2-8db5-d836183df9fc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_466a380c-a377-4bd1-aa0a-20d33c94a710" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_e0b4a57b-e212-44d2-8db5-d836183df9fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_5b248e3a-f1a3-4434-8473-84a94d7ea5e0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_466a380c-a377-4bd1-aa0a-20d33c94a710" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_5b248e3a-f1a3-4434-8473-84a94d7ea5e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PaymentsOfDebtIssuanceCostsAndDebtDiscount_14d1da3e-a763-444e-8f65-b0fed6ac6e5a" xlink:href="shc-20241231.xsd#shc_PaymentsOfDebtIssuanceCostsAndDebtDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_466a380c-a377-4bd1-aa0a-20d33c94a710" xlink:to="loc_shc_PaymentsOfDebtIssuanceCostsAndDebtDiscount_14d1da3e-a763-444e-8f65-b0fed6ac6e5a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_a112d8e0-8e08-4843-90bd-50c9c386d877" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_466a380c-a377-4bd1-aa0a-20d33c94a710" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_a112d8e0-8e08-4843-90bd-50c9c386d877" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_BuyoutOfLeasedFacility_24ea89c4-41f4-4736-850e-b74a7644d16b" xlink:href="shc-20241231.xsd#shc_BuyoutOfLeasedFacility"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_466a380c-a377-4bd1-aa0a-20d33c94a710" xlink:to="loc_shc_BuyoutOfLeasedFacility_24ea89c4-41f4-4736-850e-b74a7644d16b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_af6ba29f-1713-4b4b-a674-d3c99ec573fb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_466a380c-a377-4bd1-aa0a-20d33c94a710" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_af6ba29f-1713-4b4b-a674-d3c99ec573fb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_3e8faf5c-d44b-45a4-955e-e2a27a30256c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_466a380c-a377-4bd1-aa0a-20d33c94a710" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_3e8faf5c-d44b-45a4-955e-e2a27a30256c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_0ff61730-14eb-4e64-bd64-d86a9aa715d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_466a380c-a377-4bd1-aa0a-20d33c94a710" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_0ff61730-14eb-4e64-bd64-d86a9aa715d4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_1bb9b378-8968-47a0-9b97-533167272b10" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_047688f7-8b27-41d8-b2a9-5e5d2b7085e1" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_1bb9b378-8968-47a0-9b97-533167272b10" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_34f9b5d5-8211-4deb-ab6c-286d9c980311" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_047688f7-8b27-41d8-b2a9-5e5d2b7085e1" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_34f9b5d5-8211-4deb-ab6c-286d9c980311" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_abee250c-dde8-46aa-b59f-c3a365231539" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_047688f7-8b27-41d8-b2a9-5e5d2b7085e1" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_abee250c-dde8-46aa-b59f-c3a365231539" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_222a93ab-e5e3-43f7-9a3e-808af500be0c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_8b70883f-6def-4efb-9723-4e56abb9cd7f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_047688f7-8b27-41d8-b2a9-5e5d2b7085e1" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_8b70883f-6def-4efb-9723-4e56abb9cd7f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_82ba0193-e701-406e-bbe4-58e95a0f039c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_8b70883f-6def-4efb-9723-4e56abb9cd7f" xlink:to="loc_us-gaap_InterestPaidNet_82ba0193-e701-406e-bbe4-58e95a0f039c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_31cc0fe2-a0cd-48e2-8cc2-9d3cb0e20862" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_8b70883f-6def-4efb-9723-4e56abb9cd7f" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_31cc0fe2-a0cd-48e2-8cc2-9d3cb0e20862" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_8d390eb9-4a66-41c9-bd68-eb3582ea6d20" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CapitalExpendituresIncurredButNotYetPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_8b70883f-6def-4efb-9723-4e56abb9cd7f" xlink:to="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_8d390eb9-4a66-41c9-bd68-eb3582ea6d20" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/ConsolidatedStatementsofEquity" xlink:type="simple" xlink:href="shc-20241231.xsd#ConsolidatedStatementsofEquity"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/ConsolidatedStatementsofEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_042b17f8-302f-4a0c-9345-3d4a1faffbf8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_e0c17582-f574-49a0-9c4e-a0c8ed9fe687" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_042b17f8-302f-4a0c-9345-3d4a1faffbf8" xlink:to="loc_us-gaap_StatementTable_e0c17582-f574-49a0-9c4e-a0c8ed9fe687" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_a350027c-e055-48a2-a5a4-8eef99548a71" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_e0c17582-f574-49a0-9c4e-a0c8ed9fe687" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_a350027c-e055-48a2-a5a4-8eef99548a71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_a350027c-e055-48a2-a5a4-8eef99548a71_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_a350027c-e055-48a2-a5a4-8eef99548a71" xlink:to="loc_us-gaap_EquityComponentDomain_a350027c-e055-48a2-a5a4-8eef99548a71_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_ca650d98-848b-4f5b-94ec-404ce2eda64a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_a350027c-e055-48a2-a5a4-8eef99548a71" xlink:to="loc_us-gaap_EquityComponentDomain_ca650d98-848b-4f5b-94ec-404ce2eda64a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_48a2ebc7-50c6-4840-a82b-60fbe5e1ce96" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_ca650d98-848b-4f5b-94ec-404ce2eda64a" xlink:to="loc_us-gaap_CommonStockMember_48a2ebc7-50c6-4840-a82b-60fbe5e1ce96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_5c076b6e-288a-4f61-8e58-2f7871b682ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_ca650d98-848b-4f5b-94ec-404ce2eda64a" xlink:to="loc_us-gaap_TreasuryStockCommonMember_5c076b6e-288a-4f61-8e58-2f7871b682ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_37aed5b6-a70f-4d3d-a81d-0afc8a4853f7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_ca650d98-848b-4f5b-94ec-404ce2eda64a" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_37aed5b6-a70f-4d3d-a81d-0afc8a4853f7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_f7a00ca5-c811-4382-b489-a20196c70836" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_ca650d98-848b-4f5b-94ec-404ce2eda64a" xlink:to="loc_us-gaap_RetainedEarningsMember_f7a00ca5-c811-4382-b489-a20196c70836" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_46d3f153-c901-43aa-88e5-d9f27a18d01b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_ca650d98-848b-4f5b-94ec-404ce2eda64a" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_46d3f153-c901-43aa-88e5-d9f27a18d01b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2d97a12c-16a1-426a-94dc-cbafc3ad33fb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_042b17f8-302f-4a0c-9345-3d4a1faffbf8" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2d97a12c-16a1-426a-94dc-cbafc3ad33fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_3409bc60-7450-4e15-b376-40bef14a986b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2d97a12c-16a1-426a-94dc-cbafc3ad33fb" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_3409bc60-7450-4e15-b376-40bef14a986b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_2ffa42fc-aa6f-48cb-b826-c7f7e9fb15fd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2d97a12c-16a1-426a-94dc-cbafc3ad33fb" xlink:to="loc_us-gaap_StockholdersEquity_2ffa42fc-aa6f-48cb-b826-c7f7e9fb15fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_b4b25c76-b7f7-45f2-bbc6-144dbea548cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2d97a12c-16a1-426a-94dc-cbafc3ad33fb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_b4b25c76-b7f7-45f2-bbc6-144dbea548cc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_f5000efe-3b8b-4859-aa55-ef159941f044" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2d97a12c-16a1-426a-94dc-cbafc3ad33fb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_f5000efe-3b8b-4859-aa55-ef159941f044" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_2aae9b48-7f8a-42ea-a30e-2e718a684fe0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2d97a12c-16a1-426a-94dc-cbafc3ad33fb" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_2aae9b48-7f8a-42ea-a30e-2e718a684fe0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_37e634db-cace-4dd0-86cd-6bb991c7c9db" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_2aae9b48-7f8a-42ea-a30e-2e718a684fe0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_37e634db-cace-4dd0-86cd-6bb991c7c9db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_b6a2e699-6bcd-4aed-b4ee-d44a1a0ec4b8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_2aae9b48-7f8a-42ea-a30e-2e718a684fe0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_b6a2e699-6bcd-4aed-b4ee-d44a1a0ec4b8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax_67819471-536a-475d-8dc0-bc41db880b59" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_2aae9b48-7f8a-42ea-a30e-2e718a684fe0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax_67819471-536a-475d-8dc0-bc41db880b59" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_36fe545b-e980-4b9e-a6a9-1a9f648cf2ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_2aae9b48-7f8a-42ea-a30e-2e718a684fe0" xlink:to="loc_us-gaap_NetIncomeLoss_36fe545b-e980-4b9e-a6a9-1a9f648cf2ee" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_acaf7ce9-4fa0-4556-8a89-521870735af2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_e390fabb-c427-4c93-b934-f1ffaaa6c57d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/SignificantAccountingPoliciesAdditionalInformationDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#SignificantAccountingPoliciesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/SignificantAccountingPoliciesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13c1a409-beae-453f-bad7-1d14714cc31b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ca174f73-519d-41f6-89ae-81f4f8f5ffb6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13c1a409-beae-453f-bad7-1d14714cc31b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ca174f73-519d-41f6-89ae-81f4f8f5ffb6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_ebf51cfa-2f74-4edd-ba01-a3b73cbf771c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ca174f73-519d-41f6-89ae-81f4f8f5ffb6" xlink:to="loc_us-gaap_StatementClassOfStockAxis_ebf51cfa-2f74-4edd-ba01-a3b73cbf771c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_ebf51cfa-2f74-4edd-ba01-a3b73cbf771c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_ebf51cfa-2f74-4edd-ba01-a3b73cbf771c" xlink:to="loc_us-gaap_ClassOfStockDomain_ebf51cfa-2f74-4edd-ba01-a3b73cbf771c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0291730c-67b1-42fc-87af-5bf50e40cd11" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_ebf51cfa-2f74-4edd-ba01-a3b73cbf771c" xlink:to="loc_us-gaap_ClassOfStockDomain_0291730c-67b1-42fc-87af-5bf50e40cd11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PreIPOB1Member_f4993063-2def-4610-a8eb-13f2a0017cb7" xlink:href="shc-20241231.xsd#shc_PreIPOB1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0291730c-67b1-42fc-87af-5bf50e40cd11" xlink:to="loc_shc_PreIPOB1Member_f4993063-2def-4610-a8eb-13f2a0017cb7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_63cc5a9f-d61c-4fe2-8413-fe5998a7a18f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ca174f73-519d-41f6-89ae-81f4f8f5ffb6" xlink:to="loc_us-gaap_AwardTypeAxis_63cc5a9f-d61c-4fe2-8413-fe5998a7a18f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_63cc5a9f-d61c-4fe2-8413-fe5998a7a18f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_63cc5a9f-d61c-4fe2-8413-fe5998a7a18f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_63cc5a9f-d61c-4fe2-8413-fe5998a7a18f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ceda3718-a2b7-406a-9599-a93471a5b66a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_63cc5a9f-d61c-4fe2-8413-fe5998a7a18f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ceda3718-a2b7-406a-9599-a93471a5b66a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_c5973a6b-5656-4575-b53c-0232e36c947a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ceda3718-a2b7-406a-9599-a93471a5b66a" xlink:to="loc_us-gaap_PerformanceSharesMember_c5973a6b-5656-4575-b53c-0232e36c947a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_2b5970ed-add9-4f28-b943-41efd0e12f08" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ca174f73-519d-41f6-89ae-81f4f8f5ffb6" xlink:to="loc_srt_RangeAxis_2b5970ed-add9-4f28-b943-41efd0e12f08" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_2b5970ed-add9-4f28-b943-41efd0e12f08_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_2b5970ed-add9-4f28-b943-41efd0e12f08" xlink:to="loc_srt_RangeMember_2b5970ed-add9-4f28-b943-41efd0e12f08_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_3e80476f-62d1-48b3-8fa1-f60b11d70dd1" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_2b5970ed-add9-4f28-b943-41efd0e12f08" xlink:to="loc_srt_RangeMember_3e80476f-62d1-48b3-8fa1-f60b11d70dd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_036d0f16-b948-44f6-8abb-b1638dcdb438" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3e80476f-62d1-48b3-8fa1-f60b11d70dd1" xlink:to="loc_srt_MinimumMember_036d0f16-b948-44f6-8abb-b1638dcdb438" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_e46a37d1-ff8f-4869-b12a-fb12af0635b2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3e80476f-62d1-48b3-8fa1-f60b11d70dd1" xlink:to="loc_srt_MaximumMember_e46a37d1-ff8f-4869-b12a-fb12af0635b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_60f47834-b08c-4c14-996a-d1c24712032c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ca174f73-519d-41f6-89ae-81f4f8f5ffb6" xlink:to="loc_us-gaap_PlanNameAxis_60f47834-b08c-4c14-996a-d1c24712032c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_60f47834-b08c-4c14-996a-d1c24712032c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_60f47834-b08c-4c14-996a-d1c24712032c" xlink:to="loc_us-gaap_PlanNameDomain_60f47834-b08c-4c14-996a-d1c24712032c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_272d2135-d26b-4b04-b988-30ad53d4b073" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_60f47834-b08c-4c14-996a-d1c24712032c" xlink:to="loc_us-gaap_PlanNameDomain_272d2135-d26b-4b04-b988-30ad53d4b073" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_A2020OmnibusIncentivePlanMember_6fb30458-725c-4b40-90bb-1f16ef86c062" xlink:href="shc-20241231.xsd#shc_A2020OmnibusIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_272d2135-d26b-4b04-b988-30ad53d4b073" xlink:to="loc_shc_A2020OmnibusIncentivePlanMember_6fb30458-725c-4b40-90bb-1f16ef86c062" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_f5141fd6-b77e-4396-a299-0f3984599091" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13c1a409-beae-453f-bad7-1d14714cc31b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_f5141fd6-b77e-4396-a299-0f3984599091" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/SignificantAccountingPoliciesPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#SignificantAccountingPoliciesPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/SignificantAccountingPoliciesPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_098b1181-824f-4342-86f9-5d0d6a052a8f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_805feea3-1ce3-4376-9544-c0c75215de1c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_098b1181-824f-4342-86f9-5d0d6a052a8f" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_805feea3-1ce3-4376-9544-c0c75215de1c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_caea384c-1038-40ab-b9a6-72926ecf3c8a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_805feea3-1ce3-4376-9544-c0c75215de1c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_caea384c-1038-40ab-b9a6-72926ecf3c8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_caea384c-1038-40ab-b9a6-72926ecf3c8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_caea384c-1038-40ab-b9a6-72926ecf3c8a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_caea384c-1038-40ab-b9a6-72926ecf3c8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_99735bb5-80ce-4a18-a828-046f1d1d11d8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_caea384c-1038-40ab-b9a6-72926ecf3c8a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_99735bb5-80ce-4a18-a828-046f1d1d11d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_RadioactiveIsotopeMember_2abc0afd-fecb-4fab-8203-c3f6ccfc29a1" xlink:href="shc-20241231.xsd#shc_RadioactiveIsotopeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_99735bb5-80ce-4a18-a828-046f1d1d11d8" xlink:to="loc_shc_RadioactiveIsotopeMember_2abc0afd-fecb-4fab-8203-c3f6ccfc29a1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SoftwarePurchasesAndSoftwareDevelopmentMember_fbb04a3e-0b36-403e-bd8f-3ec94f9e22bb" xlink:href="shc-20241231.xsd#shc_SoftwarePurchasesAndSoftwareDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_99735bb5-80ce-4a18-a828-046f1d1d11d8" xlink:to="loc_shc_SoftwarePurchasesAndSoftwareDevelopmentMember_fbb04a3e-0b36-403e-bd8f-3ec94f9e22bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_21c5c3e5-671b-49f0-a45c-569b3f61b49c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BuildingAndBuildingImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_99735bb5-80ce-4a18-a828-046f1d1d11d8" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_21c5c3e5-671b-49f0-a45c-569b3f61b49c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_dd5985bb-dd78-4594-a816-fd690ca445b5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_99735bb5-80ce-4a18-a828-046f1d1d11d8" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_dd5985bb-dd78-4594-a816-fd690ca445b5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdsAndLeaseholdImprovementsMember_19cd8246-4199-4174-9eb0-780260caa7a6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LeaseholdsAndLeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_99735bb5-80ce-4a18-a828-046f1d1d11d8" xlink:to="loc_us-gaap_LeaseholdsAndLeaseholdImprovementsMember_19cd8246-4199-4174-9eb0-780260caa7a6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_8474baff-1980-4f43-919a-87011fa30bd6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_99735bb5-80ce-4a18-a828-046f1d1d11d8" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_8474baff-1980-4f43-919a-87011fa30bd6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_a941517e-7673-4489-86b1-d51373dcf99a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_99735bb5-80ce-4a18-a828-046f1d1d11d8" xlink:to="loc_us-gaap_ComputerEquipmentMember_a941517e-7673-4489-86b1-d51373dcf99a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a1d87a97-b2c2-4a69-8316-7f0eba6f2235" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_805feea3-1ce3-4376-9544-c0c75215de1c" xlink:to="loc_srt_RangeAxis_a1d87a97-b2c2-4a69-8316-7f0eba6f2235" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a1d87a97-b2c2-4a69-8316-7f0eba6f2235_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a1d87a97-b2c2-4a69-8316-7f0eba6f2235" xlink:to="loc_srt_RangeMember_a1d87a97-b2c2-4a69-8316-7f0eba6f2235_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_3674fe78-6b76-40b4-8a21-9f6c02d24bb8" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a1d87a97-b2c2-4a69-8316-7f0eba6f2235" xlink:to="loc_srt_RangeMember_3674fe78-6b76-40b4-8a21-9f6c02d24bb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_4ff5e173-aa87-4978-bf27-4b27bd7b250e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3674fe78-6b76-40b4-8a21-9f6c02d24bb8" xlink:to="loc_srt_MinimumMember_4ff5e173-aa87-4978-bf27-4b27bd7b250e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_8ba94ab9-ce0f-4be9-b43e-73bba1f21bb3" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3674fe78-6b76-40b4-8a21-9f6c02d24bb8" xlink:to="loc_srt_MaximumMember_8ba94ab9-ce0f-4be9-b43e-73bba1f21bb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_02f23356-41bd-4f80-b32a-9c056f886fd0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_098b1181-824f-4342-86f9-5d0d6a052a8f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_02f23356-41bd-4f80-b32a-9c056f886fd0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedComputerSoftwareGross_ecd759af-934c-4b95-976c-da1c2b35c71a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CapitalizedComputerSoftwareGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_098b1181-824f-4342-86f9-5d0d6a052a8f" xlink:to="loc_us-gaap_CapitalizedComputerSoftwareGross_ecd759af-934c-4b95-976c-da1c2b35c71a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_68079ef6-dc41-4402-baba-003ed6a2b38f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_098b1181-824f-4342-86f9-5d0d6a052a8f" xlink:to="loc_us-gaap_Depreciation_68079ef6-dc41-4402-baba-003ed6a2b38f" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/RevenueRecognitionDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#RevenueRecognitionDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/RevenueRecognitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_35264266-e960-44dd-b40d-5f3a5b3d3865" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_1a62c4b0-c352-4418-adcb-68d60bdeadbb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_35264266-e960-44dd-b40d-5f3a5b3d3865" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_1a62c4b0-c352-4418-adcb-68d60bdeadbb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_fd61ac1a-07e7-40b0-bf0e-48fec3498083" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_1a62c4b0-c352-4418-adcb-68d60bdeadbb" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_fd61ac1a-07e7-40b0-bf0e-48fec3498083" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_fd61ac1a-07e7-40b0-bf0e-48fec3498083_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_fd61ac1a-07e7-40b0-bf0e-48fec3498083" xlink:to="loc_us-gaap_SegmentDomain_fd61ac1a-07e7-40b0-bf0e-48fec3498083_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_d8255373-a47d-46a7-a82f-266287d4ff51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_fd61ac1a-07e7-40b0-bf0e-48fec3498083" xlink:to="loc_us-gaap_SegmentDomain_d8255373-a47d-46a7-a82f-266287d4ff51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SterigenicsMember_2e6abc57-137e-49d3-8ea1-51cf9f343a47" xlink:href="shc-20241231.xsd#shc_SterigenicsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_d8255373-a47d-46a7-a82f-266287d4ff51" xlink:to="loc_shc_SterigenicsMember_2e6abc57-137e-49d3-8ea1-51cf9f343a47" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NordionMember_f58e0a28-e22f-4203-957b-19c1aded7988" xlink:href="shc-20241231.xsd#shc_NordionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_d8255373-a47d-46a7-a82f-266287d4ff51" xlink:to="loc_shc_NordionMember_f58e0a28-e22f-4203-957b-19c1aded7988" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NelsonLabsMember_090f6594-a778-4e68-830d-97b4bb492e62" xlink:href="shc-20241231.xsd#shc_NelsonLabsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_d8255373-a47d-46a7-a82f-266287d4ff51" xlink:to="loc_shc_NelsonLabsMember_090f6594-a778-4e68-830d-97b4bb492e62" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_970a1e64-f5f2-4013-9610-5552c25bfb24" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimingOfTransferOfGoodOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_1a62c4b0-c352-4418-adcb-68d60bdeadbb" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_970a1e64-f5f2-4013-9610-5552c25bfb24" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_970a1e64-f5f2-4013-9610-5552c25bfb24_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_970a1e64-f5f2-4013-9610-5552c25bfb24" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_970a1e64-f5f2-4013-9610-5552c25bfb24_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_a3316ff3-6717-48a8-8cd1-c4f8cc67353f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_970a1e64-f5f2-4013-9610-5552c25bfb24" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_a3316ff3-6717-48a8-8cd1-c4f8cc67353f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredAtPointInTimeMember_1d6e971b-f6ef-4265-b96f-9bc2c37b83a7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransferredAtPointInTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_a3316ff3-6717-48a8-8cd1-c4f8cc67353f" xlink:to="loc_us-gaap_TransferredAtPointInTimeMember_1d6e971b-f6ef-4265-b96f-9bc2c37b83a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredOverTimeMember_502bea23-c5da-47b7-ac34-957cf68ecab0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransferredOverTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_a3316ff3-6717-48a8-8cd1-c4f8cc67353f" xlink:to="loc_us-gaap_TransferredOverTimeMember_502bea23-c5da-47b7-ac34-957cf68ecab0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_5145a9bc-38f5-41ca-a15c-704f694762de" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_35264266-e960-44dd-b40d-5f3a5b3d3865" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_5145a9bc-38f5-41ca-a15c-704f694762de" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_7ae8b5b8-a5d4-46b5-adac-bf72ad97bebd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_5b97bc5b-57f7-4126-b6c0-2f88bab962ff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_7ae8b5b8-a5d4-46b5-adac-bf72ad97bebd" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_5b97bc5b-57f7-4126-b6c0-2f88bab962ff" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_0d508569-fd17-400b-96f6-efe5466ab48d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_5b97bc5b-57f7-4126-b6c0-2f88bab962ff" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_0d508569-fd17-400b-96f6-efe5466ab48d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_0d508569-fd17-400b-96f6-efe5466ab48d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_0d508569-fd17-400b-96f6-efe5466ab48d" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_0d508569-fd17-400b-96f6-efe5466ab48d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_546c7f09-f42c-49a7-ba9f-17dcc055c3e0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_0d508569-fd17-400b-96f6-efe5466ab48d" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_546c7f09-f42c-49a7-ba9f-17dcc055c3e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandAndBuildingMember_663ad539-12ee-4c52-9c23-0acde6e3183d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LandAndBuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_546c7f09-f42c-49a7-ba9f-17dcc055c3e0" xlink:to="loc_us-gaap_LandAndBuildingMember_663ad539-12ee-4c52-9c23-0acde6e3183d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdsAndLeaseholdImprovementsMember_3649b746-ed7c-40ce-8214-66d784d27c56" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LeaseholdsAndLeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_546c7f09-f42c-49a7-ba9f-17dcc055c3e0" xlink:to="loc_us-gaap_LeaseholdsAndLeaseholdImprovementsMember_3649b746-ed7c-40ce-8214-66d784d27c56" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_e2d85b33-b0ab-463e-bcfc-a40b133eb856" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_546c7f09-f42c-49a7-ba9f-17dcc055c3e0" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_e2d85b33-b0ab-463e-bcfc-a40b133eb856" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_9fb8905d-7edc-4941-9ffe-9c8fb7082fdd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_546c7f09-f42c-49a7-ba9f-17dcc055c3e0" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_9fb8905d-7edc-4941-9ffe-9c8fb7082fdd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_ada32b9f-036b-41c8-b40a-c8072e4808da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_546c7f09-f42c-49a7-ba9f-17dcc055c3e0" xlink:to="loc_us-gaap_ComputerEquipmentMember_ada32b9f-036b-41c8-b40a-c8072e4808da" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationCostsMember_7fa138be-0613-4c11-820b-73bc17003d3f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetRetirementObligationCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_546c7f09-f42c-49a7-ba9f-17dcc055c3e0" xlink:to="loc_us-gaap_AssetRetirementObligationCostsMember_7fa138be-0613-4c11-820b-73bc17003d3f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_82473726-5863-4419-89f4-a0bed7c95487" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_546c7f09-f42c-49a7-ba9f-17dcc055c3e0" xlink:to="loc_us-gaap_ConstructionInProgressMember_82473726-5863-4419-89f4-a0bed7c95487" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_23c69a50-b469-46d4-9ce9-63d24830f93b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_7ae8b5b8-a5d4-46b5-adac-bf72ad97bebd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_23c69a50-b469-46d4-9ce9-63d24830f93b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_eeb446d8-cec1-4bf3-ab54-45e03d9ba6b8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_7ae8b5b8-a5d4-46b5-adac-bf72ad97bebd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_eeb446d8-cec1-4bf3-ab54-45e03d9ba6b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_5e006288-9e08-4d33-8065-e1f6b297b6a5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_7ae8b5b8-a5d4-46b5-adac-bf72ad97bebd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_5e006288-9e08-4d33-8065-e1f6b297b6a5" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/GoodwillandOtherIntangibleAssetsScheduleofGoodwillDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#GoodwillandOtherIntangibleAssetsScheduleofGoodwillDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/GoodwillandOtherIntangibleAssetsScheduleofGoodwillDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_0e5ad0ac-22d5-4811-8e00-0a1e591f422f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_86e2a0c5-5c62-4bc4-8da1-226c31b519e7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_0e5ad0ac-22d5-4811-8e00-0a1e591f422f" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_86e2a0c5-5c62-4bc4-8da1-226c31b519e7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_7eea5d78-e747-4d66-bc03-36445b173c10" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_86e2a0c5-5c62-4bc4-8da1-226c31b519e7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_7eea5d78-e747-4d66-bc03-36445b173c10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_7eea5d78-e747-4d66-bc03-36445b173c10_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7eea5d78-e747-4d66-bc03-36445b173c10" xlink:to="loc_us-gaap_SegmentDomain_7eea5d78-e747-4d66-bc03-36445b173c10_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1f161a8f-c1ed-4286-a300-bbf7fbdb515d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7eea5d78-e747-4d66-bc03-36445b173c10" xlink:to="loc_us-gaap_SegmentDomain_1f161a8f-c1ed-4286-a300-bbf7fbdb515d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SterigenicsMember_160d60ca-8f53-4fe5-a8a4-8020827f01e6" xlink:href="shc-20241231.xsd#shc_SterigenicsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1f161a8f-c1ed-4286-a300-bbf7fbdb515d" xlink:to="loc_shc_SterigenicsMember_160d60ca-8f53-4fe5-a8a4-8020827f01e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NordionMember_06699e87-740a-4e74-91c7-93cb875f641a" xlink:href="shc-20241231.xsd#shc_NordionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1f161a8f-c1ed-4286-a300-bbf7fbdb515d" xlink:to="loc_shc_NordionMember_06699e87-740a-4e74-91c7-93cb875f641a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NelsonLabsMember_33764eec-0ba2-4cce-9361-35ea60e150ac" xlink:href="shc-20241231.xsd#shc_NelsonLabsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1f161a8f-c1ed-4286-a300-bbf7fbdb515d" xlink:to="loc_shc_NelsonLabsMember_33764eec-0ba2-4cce-9361-35ea60e150ac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_947e9f62-8f15-41eb-b12c-8316c363e84f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_0e5ad0ac-22d5-4811-8e00-0a1e591f422f" xlink:to="loc_us-gaap_GoodwillRollForward_947e9f62-8f15-41eb-b12c-8316c363e84f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_3c645f5b-14db-4ee9-9c0c-4be62ba57334" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_947e9f62-8f15-41eb-b12c-8316c363e84f" xlink:to="loc_us-gaap_Goodwill_3c645f5b-14db-4ee9-9c0c-4be62ba57334" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_2a57d1b9-6314-4977-901d-5a9cf2503298" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_947e9f62-8f15-41eb-b12c-8316c363e84f" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_2a57d1b9-6314-4977-901d-5a9cf2503298" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_ffb38902-5195-40ff-bd09-3164fe5acd62" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/GoodwillandOtherIntangibleAssetsScheduleofAcquiredFiniteLivedandIndefiniteLivedIntangibleAssetsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#GoodwillandOtherIntangibleAssetsScheduleofAcquiredFiniteLivedandIndefiniteLivedIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/GoodwillandOtherIntangibleAssetsScheduleofAcquiredFiniteLivedandIndefiniteLivedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_61b3e493-79fc-4638-9b67-dff2ed44a2b7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_f514f2cd-c597-41a1-8a89-647a66db5a20" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_61b3e493-79fc-4638-9b67-dff2ed44a2b7" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_f514f2cd-c597-41a1-8a89-647a66db5a20" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d25a3984-37d0-45a6-b033-ad6048a605c7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_f514f2cd-c597-41a1-8a89-647a66db5a20" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d25a3984-37d0-45a6-b033-ad6048a605c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d25a3984-37d0-45a6-b033-ad6048a605c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d25a3984-37d0-45a6-b033-ad6048a605c7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d25a3984-37d0-45a6-b033-ad6048a605c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8bb76ba7-3567-4449-92ee-530af1631469" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d25a3984-37d0-45a6-b033-ad6048a605c7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8bb76ba7-3567-4449-92ee-530af1631469" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_471915c6-e390-4087-8ff3-0b91081fec8c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8bb76ba7-3567-4449-92ee-530af1631469" xlink:to="loc_us-gaap_CustomerRelationshipsMember_471915c6-e390-4087-8ff3-0b91081fec8c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_9d8d4906-138e-422b-9355-102abdda2fcd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8bb76ba7-3567-4449-92ee-530af1631469" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_9d8d4906-138e-422b-9355-102abdda2fcd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_11938f79-30f0-4c47-b5d2-98589a2fb3e8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8bb76ba7-3567-4449-92ee-530af1631469" xlink:to="loc_us-gaap_TradeNamesMember_11938f79-30f0-4c47-b5d2-98589a2fb3e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LandUseRightsMember_01056c07-fea8-4457-937a-53e4e9bfe068" xlink:href="shc-20241231.xsd#shc_LandUseRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8bb76ba7-3567-4449-92ee-530af1631469" xlink:to="loc_shc_LandUseRightsMember_01056c07-fea8-4457-937a-53e4e9bfe068" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SealedSourceAndSupplyAgreementsMember_cb42c77f-6e0f-4903-862c-67eec9fe28f9" xlink:href="shc-20241231.xsd#shc_SealedSourceAndSupplyAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8bb76ba7-3567-4449-92ee-530af1631469" xlink:to="loc_shc_SealedSourceAndSupplyAgreementsMember_cb42c77f-6e0f-4903-862c-67eec9fe28f9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_dbf3ccfe-0594-41f7-abd3-4af819f2b329" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8bb76ba7-3567-4449-92ee-530af1631469" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_dbf3ccfe-0594-41f7-abd3-4af819f2b329" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_baa0535f-63b3-4f99-beec-6c291faf5738" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_61b3e493-79fc-4638-9b67-dff2ed44a2b7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_baa0535f-63b3-4f99-beec-6c291faf5738" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_eda4781b-af8b-41fa-b761-8f89728784f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_61b3e493-79fc-4638-9b67-dff2ed44a2b7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_eda4781b-af8b-41fa-b761-8f89728784f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_300e7e63-159e-473f-8328-6380471c5e2f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_cb6da196-5aa4-42a5-baa0-12f64c937d0b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_300e7e63-159e-473f-8328-6380471c5e2f" xlink:to="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_cb6da196-5aa4-42a5-baa0-12f64c937d0b" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_7170b9cf-0e05-4995-947c-cf89e955f487" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_cb6da196-5aa4-42a5-baa0-12f64c937d0b" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_7170b9cf-0e05-4995-947c-cf89e955f487" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_7170b9cf-0e05-4995-947c-cf89e955f487_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_7170b9cf-0e05-4995-947c-cf89e955f487" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_7170b9cf-0e05-4995-947c-cf89e955f487_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_8ccfa203-f46a-47a4-82b0-df7fbf67c089" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_7170b9cf-0e05-4995-947c-cf89e955f487" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_8ccfa203-f46a-47a4-82b0-df7fbf67c089" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_e474c91e-4377-41e4-99dd-e3334b206268" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_8ccfa203-f46a-47a4-82b0-df7fbf67c089" xlink:to="loc_us-gaap_LicensingAgreementsMember_e474c91e-4377-41e4-99dd-e3334b206268" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_3c82c905-f6c6-4bea-83d1-91ab63ff0f3c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TrademarksAndTradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_8ccfa203-f46a-47a4-82b0-df7fbf67c089" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_3c82c905-f6c6-4bea-83d1-91ab63ff0f3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_98db99c4-9b9d-489a-974f-311e7f9b50ca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_300e7e63-159e-473f-8328-6380471c5e2f" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_98db99c4-9b9d-489a-974f-311e7f9b50ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LicensingAgreementsRenewalTerm_37ce25f0-2426-4f80-8e0c-068f2ced44cc" xlink:href="shc-20241231.xsd#shc_LicensingAgreementsRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_300e7e63-159e-473f-8328-6380471c5e2f" xlink:to="loc_shc_LicensingAgreementsRenewalTerm_37ce25f0-2426-4f80-8e0c-068f2ced44cc" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/GoodwillandOtherIntangibleAssetsAdditionalInformationDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#GoodwillandOtherIntangibleAssetsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/GoodwillandOtherIntangibleAssetsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_bcbc8482-2d1a-486f-966d-920d4b707f2c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0f6edaeb-0c7a-400a-85e7-41b1fc2d35ea" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_bcbc8482-2d1a-486f-966d-920d4b707f2c" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0f6edaeb-0c7a-400a-85e7-41b1fc2d35ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c8cb210a-6b2c-4809-9b7c-2f9431c1294a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0f6edaeb-0c7a-400a-85e7-41b1fc2d35ea" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c8cb210a-6b2c-4809-9b7c-2f9431c1294a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c8cb210a-6b2c-4809-9b7c-2f9431c1294a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c8cb210a-6b2c-4809-9b7c-2f9431c1294a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c8cb210a-6b2c-4809-9b7c-2f9431c1294a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_75c7d091-1c1f-4eae-ab4c-0a5118fffb10" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c8cb210a-6b2c-4809-9b7c-2f9431c1294a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_75c7d091-1c1f-4eae-ab4c-0a5118fffb10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_8499db51-3745-4a3d-888e-e87c6410c305" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_75c7d091-1c1f-4eae-ab4c-0a5118fffb10" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_8499db51-3745-4a3d-888e-e87c6410c305" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_7cb6ca35-9eaa-4ead-8c12-a965b799fd61" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0f6edaeb-0c7a-400a-85e7-41b1fc2d35ea" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_7cb6ca35-9eaa-4ead-8c12-a965b799fd61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_7cb6ca35-9eaa-4ead-8c12-a965b799fd61_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_7cb6ca35-9eaa-4ead-8c12-a965b799fd61" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_7cb6ca35-9eaa-4ead-8c12-a965b799fd61_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_f03e9be2-1857-426c-b366-01e3d5c375e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_7cb6ca35-9eaa-4ead-8c12-a965b799fd61" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_f03e9be2-1857-426c-b366-01e3d5c375e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_AmortizationOfIntangibleAssetsNonproductionMember_3faef21a-c9c1-4e91-ba6d-107a15fc0fa5" xlink:href="shc-20241231.xsd#shc_AmortizationOfIntangibleAssetsNonproductionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_f03e9be2-1857-426c-b366-01e3d5c375e1" xlink:to="loc_shc_AmortizationOfIntangibleAssetsNonproductionMember_3faef21a-c9c1-4e91-ba6d-107a15fc0fa5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_4e169879-6cec-4412-afa9-8c0fc9039e96" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_bcbc8482-2d1a-486f-966d-920d4b707f2c" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_4e169879-6cec-4412-afa9-8c0fc9039e96" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/GoodwillandOtherIntangibleAssetsScheduleofWeightedAverageRemainingAmortizationDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#GoodwillandOtherIntangibleAssetsScheduleofWeightedAverageRemainingAmortizationDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/GoodwillandOtherIntangibleAssetsScheduleofWeightedAverageRemainingAmortizationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_929ebb55-6633-44f4-9203-3f09b2d07d36" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_e3939440-e3b4-4636-a678-da0c27780d34" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_929ebb55-6633-44f4-9203-3f09b2d07d36" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_e3939440-e3b4-4636-a678-da0c27780d34" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_f1721abd-976c-4a9b-8a47-95c74dbe9484" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_e3939440-e3b4-4636-a678-da0c27780d34" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_f1721abd-976c-4a9b-8a47-95c74dbe9484" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f1721abd-976c-4a9b-8a47-95c74dbe9484_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_f1721abd-976c-4a9b-8a47-95c74dbe9484" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f1721abd-976c-4a9b-8a47-95c74dbe9484_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3855ce5f-daf4-4bce-954a-cdfb4cdf12b0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_f1721abd-976c-4a9b-8a47-95c74dbe9484" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3855ce5f-daf4-4bce-954a-cdfb4cdf12b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_ac5ccc90-2588-4ebb-a938-5b8d6d8ca416" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3855ce5f-daf4-4bce-954a-cdfb4cdf12b0" xlink:to="loc_us-gaap_CustomerRelationshipsMember_ac5ccc90-2588-4ebb-a938-5b8d6d8ca416" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_abb8b951-dfc7-4f1d-bf69-9a0df82cb07b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3855ce5f-daf4-4bce-954a-cdfb4cdf12b0" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_abb8b951-dfc7-4f1d-bf69-9a0df82cb07b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_6f52f5b3-0662-43ac-b149-6bd1d3568d7e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3855ce5f-daf4-4bce-954a-cdfb4cdf12b0" xlink:to="loc_us-gaap_TradeNamesMember_6f52f5b3-0662-43ac-b149-6bd1d3568d7e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LandUseRightsMember_77865cda-8f06-425f-9234-4a0f3cd82232" xlink:href="shc-20241231.xsd#shc_LandUseRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3855ce5f-daf4-4bce-954a-cdfb4cdf12b0" xlink:to="loc_shc_LandUseRightsMember_77865cda-8f06-425f-9234-4a0f3cd82232" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SealedSourceAndSupplyAgreementsMember_7d8e0aec-da31-4747-968a-c6b3e12dd870" xlink:href="shc-20241231.xsd#shc_SealedSourceAndSupplyAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3855ce5f-daf4-4bce-954a-cdfb4cdf12b0" xlink:to="loc_shc_SealedSourceAndSupplyAgreementsMember_7d8e0aec-da31-4747-968a-c6b3e12dd870" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_9d41771d-69e0-43ca-8da3-aa7ba672cba3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3855ce5f-daf4-4bce-954a-cdfb4cdf12b0" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_9d41771d-69e0-43ca-8da3-aa7ba672cba3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_97ac10dd-edf2-4955-a306-dbf54ce02bd4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_929ebb55-6633-44f4-9203-3f09b2d07d36" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_97ac10dd-edf2-4955-a306-dbf54ce02bd4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/AccruedLiabilitiesDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#AccruedLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/AccruedLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:href="shc-20241231.xsd#shc_AccountsPayableAndAccruedLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_AccountsPayableAndAccruedLiabilitiesTable_2425d3d3-add4-4750-ad5a-4b6872dbaeec" xlink:href="shc-20241231.xsd#shc_AccountsPayableAndAccruedLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_shc_AccountsPayableAndAccruedLiabilitiesTable_2425d3d3-add4-4750-ad5a-4b6872dbaeec" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_81625e18-5f75-42c2-8a60-8a56f11cc982" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesTable_2425d3d3-add4-4750-ad5a-4b6872dbaeec" xlink:to="loc_srt_LitigationCaseAxis_81625e18-5f75-42c2-8a60-8a56f11cc982" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_81625e18-5f75-42c2-8a60-8a56f11cc982_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_81625e18-5f75-42c2-8a60-8a56f11cc982" xlink:to="loc_srt_LitigationCaseTypeDomain_81625e18-5f75-42c2-8a60-8a56f11cc982_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_5868634e-aba3-4594-8ea4-8614d47d538a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_81625e18-5f75-42c2-8a60-8a56f11cc982" xlink:to="loc_srt_LitigationCaseTypeDomain_5868634e-aba3-4594-8ea4-8614d47d538a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationGeorgiaMember_10fc66ea-ff45-4e9e-9293-9a953ec109e2" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationGeorgiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_5868634e-aba3-4594-8ea4-8614d47d538a" xlink:to="loc_shc_EthyleneOxideTortLitigationGeorgiaMember_10fc66ea-ff45-4e9e-9293-9a953ec109e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationIllinoisMember_fa5e5002-5a16-4983-a1fb-f470041e1297" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationIllinoisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_5868634e-aba3-4594-8ea4-8614d47d538a" xlink:to="loc_shc_EthyleneOxideTortLitigationIllinoisMember_fa5e5002-5a16-4983-a1fb-f470041e1297" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_c094b7ac-efc3-41bf-a62d-5f7ea28f01e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_c094b7ac-efc3-41bf-a62d-5f7ea28f01e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LitigationSettlementReserveCurrent_891dc1fc-1069-4347-adfa-3c73a9d77304" xlink:href="shc-20241231.xsd#shc_LitigationSettlementReserveCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_shc_LitigationSettlementReserveCurrent_891dc1fc-1069-4347-adfa-3c73a9d77304" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationReserveCurrent_ec30be54-2721-4a9a-9d1a-d09d16af3e94" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationReserveCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_us-gaap_LitigationReserveCurrent_ec30be54-2721-4a9a-9d1a-d09d16af3e94" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_AccruedInterestExpenseCurrent_355dc023-af98-45aa-9813-6ca3879a5421" xlink:href="shc-20241231.xsd#shc_AccruedInterestExpenseCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_shc_AccruedInterestExpenseCurrent_355dc023-af98-45aa-9813-6ca3879a5421" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_5fb593b4-9b5a-4705-b277-37f8f649fc2f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_5fb593b4-9b5a-4705-b277-37f8f649fc2f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedProfessionalFeesCurrent_35fbb507-27ca-4779-95ed-44a41e7d5ea7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccruedProfessionalFeesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_us-gaap_AccruedProfessionalFeesCurrent_35fbb507-27ca-4779-95ed-44a41e7d5ea7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedUtilitiesCurrent_f836a43b-4eea-43b5-8bff-d9d07dffb4fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccruedUtilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_us-gaap_AccruedUtilitiesCurrent_f836a43b-4eea-43b5-8bff-d9d07dffb4fa" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedInsuranceCurrent_6e80d038-a744-426c-ab61-85995525e070" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccruedInsuranceCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_us-gaap_AccruedInsuranceCurrent_6e80d038-a744-426c-ab61-85995525e070" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxesPayableCurrent_c80ba60b-871f-42d7-a5b2-84b84cb35082" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TaxesPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_us-gaap_TaxesPayableCurrent_c80ba60b-871f-42d7-a5b2-84b84cb35082" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent_fbcd4944-adb2-42eb-8a39-a84b42e046a5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_us-gaap_OtherAccruedLiabilitiesCurrent_fbcd4944-adb2-42eb-8a39-a84b42e046a5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_4ca49b3d-2639-447f-86d7-e89adeb09298" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_AccountsPayableAndAccruedLiabilitiesLineItems_77594fce-c3b3-4bad-99bb-2ad49acfb05f" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_4ca49b3d-2639-447f-86d7-e89adeb09298" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/LongTermDebtScheduleofLongtermDebtDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#LongTermDebtScheduleofLongtermDebtDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/LongTermDebtScheduleofLongtermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_79896374-aec4-410b-9627-b54cb589eac5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_us-gaap_DebtInstrumentTable_79896374-aec4-410b-9627-b54cb589eac5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_c6af58ca-2890-46fd-9c37-4ab1bb295c4e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_79896374-aec4-410b-9627-b54cb589eac5" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_c6af58ca-2890-46fd-9c37-4ab1bb295c4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_c6af58ca-2890-46fd-9c37-4ab1bb295c4e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_c6af58ca-2890-46fd-9c37-4ab1bb295c4e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_c6af58ca-2890-46fd-9c37-4ab1bb295c4e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_d1fe687c-4114-40e2-9fa3-fc4cdac0f54e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_c6af58ca-2890-46fd-9c37-4ab1bb295c4e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_d1fe687c-4114-40e2-9fa3-fc4cdac0f54e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_5c80f4cb-99f7-4323-ac84-ce72e512353b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d1fe687c-4114-40e2-9fa3-fc4cdac0f54e" xlink:to="loc_us-gaap_SecuredDebtMember_5c80f4cb-99f7-4323-ac84-ce72e512353b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_8ecf7f78-c990-4e7b-a5b1-dcf6e3b5880c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_79896374-aec4-410b-9627-b54cb589eac5" xlink:to="loc_us-gaap_DebtInstrumentAxis_8ecf7f78-c990-4e7b-a5b1-dcf6e3b5880c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8ecf7f78-c990-4e7b-a5b1-dcf6e3b5880c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_8ecf7f78-c990-4e7b-a5b1-dcf6e3b5880c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8ecf7f78-c990-4e7b-a5b1-dcf6e3b5880c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_141cfcc5-c9d5-4598-b4d3-6ba713e39d32" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_8ecf7f78-c990-4e7b-a5b1-dcf6e3b5880c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_141cfcc5-c9d5-4598-b4d3-6ba713e39d32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SeniorSecuredNotesDue2031Member_e474d4a0-74a6-4de9-9b03-1e1669d0b481" xlink:href="shc-20241231.xsd#shc_SeniorSecuredNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_141cfcc5-c9d5-4598-b4d3-6ba713e39d32" xlink:to="loc_shc_SeniorSecuredNotesDue2031Member_e474d4a0-74a6-4de9-9b03-1e1669d0b481" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TermLoanDue2031Member_5ebf0442-a3ff-4d73-82ba-21adca0371f2" xlink:href="shc-20241231.xsd#shc_TermLoanDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_141cfcc5-c9d5-4598-b4d3-6ba713e39d32" xlink:to="loc_shc_TermLoanDue2031Member_5ebf0442-a3ff-4d73-82ba-21adca0371f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TermLoanDue2026Member_b7fe4bb9-8ac8-4cc1-b42a-62f56b2a8110" xlink:href="shc-20241231.xsd#shc_TermLoanDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_141cfcc5-c9d5-4598-b4d3-6ba713e39d32" xlink:to="loc_shc_TermLoanDue2026Member_b7fe4bb9-8ac8-4cc1-b42a-62f56b2a8110" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TermLoanBDue2026Member_c421f26e-7e9f-4c59-b980-930d2a634d7c" xlink:href="shc-20241231.xsd#shc_TermLoanBDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_141cfcc5-c9d5-4598-b4d3-6ba713e39d32" xlink:to="loc_shc_TermLoanBDue2026Member_c421f26e-7e9f-4c59-b980-930d2a634d7c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_ffe45749-b0c4-451a-86d5-a02fa08b94f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_ffe45749-b0c4-451a-86d5-a02fa08b94f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LongTermDebtCurrentMaturitiesGross_0eb29d7c-909a-44a9-8cc3-740ee9ea73e1" xlink:href="shc-20241231.xsd#shc_LongTermDebtCurrentMaturitiesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_shc_LongTermDebtCurrentMaturitiesGross_0eb29d7c-909a-44a9-8cc3-740ee9ea73e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LongTermDebtGrossNoncurrent_d2f058d7-6a7e-447a-967b-a78b45733a66" xlink:href="shc-20241231.xsd#shc_LongTermDebtGrossNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_shc_LongTermDebtGrossNoncurrent_d2f058d7-6a7e-447a-967b-a78b45733a66" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_5a6a1ce6-39c9-477a-8eaf-d904cfbcc5e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_5a6a1ce6-39c9-477a-8eaf-d904cfbcc5e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsCurrentNet_1e70c698-f96d-46b0-9150-04b64f7c601f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredFinanceCostsCurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_us-gaap_DeferredFinanceCostsCurrentNet_1e70c698-f96d-46b0-9150-04b64f7c601f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_6094b0dc-420a-4646-81b0-d8ab1ef4321e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_6094b0dc-420a-4646-81b0-d8ab1ef4321e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_fa59169d-c173-43f2-995b-1f29ab4156db" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_fa59169d-c173-43f2-995b-1f29ab4156db" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DebtInstrumentUnamortizedDiscountExcludingCurrentPortion_2c412273-c060-4700-88e5-7632b2673fe8" xlink:href="shc-20241231.xsd#shc_DebtInstrumentUnamortizedDiscountExcludingCurrentPortion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_shc_DebtInstrumentUnamortizedDiscountExcludingCurrentPortion_2c412273-c060-4700-88e5-7632b2673fe8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountCurrent_b688dab5-fa3d-4742-abbf-bcdfb9e23137" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentUnamortizedDiscountCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountCurrent_b688dab5-fa3d-4742-abbf-bcdfb9e23137" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_34593c7b-8335-4aa4-be52-7e44505ff65e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_us-gaap_LongTermDebt_34593c7b-8335-4aa4-be52-7e44505ff65e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_18a21133-38b3-4396-bc01-f986d580d7cf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_us-gaap_LongTermDebtCurrent_18a21133-38b3-4396-bc01-f986d580d7cf" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_a3ba2e08-3d63-4b2a-a959-7200c18b44ec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2fd52c1b-0c93-4d50-8a06-b4fa4526a221" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_a3ba2e08-3d63-4b2a-a959-7200c18b44ec" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/LongTermDebtSeniorSecuredCreditFacilitiesNarrativeDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#LongTermDebtSeniorSecuredCreditFacilitiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/LongTermDebtSeniorSecuredCreditFacilitiesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_e3fb7d98-38ee-4692-a66d-39d9a4a196d9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_DebtInstrumentTable_e3fb7d98-38ee-4692-a66d-39d9a4a196d9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_da9d240c-a112-4aba-9bc6-54682b9292fb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e3fb7d98-38ee-4692-a66d-39d9a4a196d9" xlink:to="loc_us-gaap_CreditFacilityAxis_da9d240c-a112-4aba-9bc6-54682b9292fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_da9d240c-a112-4aba-9bc6-54682b9292fb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_da9d240c-a112-4aba-9bc6-54682b9292fb" xlink:to="loc_us-gaap_CreditFacilityDomain_da9d240c-a112-4aba-9bc6-54682b9292fb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_2d602633-98f0-4f10-b81b-9641104fdf3f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_da9d240c-a112-4aba-9bc6-54682b9292fb" xlink:to="loc_us-gaap_CreditFacilityDomain_2d602633-98f0-4f10-b81b-9641104fdf3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_664153ce-9ee9-408e-9d5d-a4a71f36e680" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_2d602633-98f0-4f10-b81b-9641104fdf3f" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_664153ce-9ee9-408e-9d5d-a4a71f36e680" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_36c4d9a8-0d6a-4c27-8c3d-e7d411b35fd0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_2d602633-98f0-4f10-b81b-9641104fdf3f" xlink:to="loc_us-gaap_LineOfCreditMember_36c4d9a8-0d6a-4c27-8c3d-e7d411b35fd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_4da0f8aa-44da-459d-aa20-c9836454d53f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e3fb7d98-38ee-4692-a66d-39d9a4a196d9" xlink:to="loc_us-gaap_DebtInstrumentAxis_4da0f8aa-44da-459d-aa20-c9836454d53f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4da0f8aa-44da-459d-aa20-c9836454d53f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_4da0f8aa-44da-459d-aa20-c9836454d53f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4da0f8aa-44da-459d-aa20-c9836454d53f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_09d76808-f62b-4be8-b453-b49638353b8f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_4da0f8aa-44da-459d-aa20-c9836454d53f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_09d76808-f62b-4be8-b453-b49638353b8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SeniorSecuredCreditFacilitiesMember_41dc3c8c-a12c-4bde-b54c-bf3f551d2102" xlink:href="shc-20241231.xsd#shc_SeniorSecuredCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_09d76808-f62b-4be8-b453-b49638353b8f" xlink:to="loc_shc_SeniorSecuredCreditFacilitiesMember_41dc3c8c-a12c-4bde-b54c-bf3f551d2102" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SeniorSecuredNotesDue2031Member_cb2f3d75-4a83-4d29-9e32-b36e817014de" xlink:href="shc-20241231.xsd#shc_SeniorSecuredNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_09d76808-f62b-4be8-b453-b49638353b8f" xlink:to="loc_shc_SeniorSecuredNotesDue2031Member_cb2f3d75-4a83-4d29-9e32-b36e817014de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TermLoanDue2026Member_babbb01e-76f8-411c-8e48-b18637d64a3b" xlink:href="shc-20241231.xsd#shc_TermLoanDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_09d76808-f62b-4be8-b453-b49638353b8f" xlink:to="loc_shc_TermLoanDue2026Member_babbb01e-76f8-411c-8e48-b18637d64a3b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TermLoanBDue2026Member_3a6458f8-e7f8-48eb-860a-348bf9a0c627" xlink:href="shc-20241231.xsd#shc_TermLoanBDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_09d76808-f62b-4be8-b453-b49638353b8f" xlink:to="loc_shc_TermLoanBDue2026Member_3a6458f8-e7f8-48eb-860a-348bf9a0c627" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_FirstLienNotesDue2026Member_e46883a3-ee03-4c12-b357-7c107964eaed" xlink:href="shc-20241231.xsd#shc_FirstLienNotesDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_09d76808-f62b-4be8-b453-b49638353b8f" xlink:to="loc_shc_FirstLienNotesDue2026Member_e46883a3-ee03-4c12-b357-7c107964eaed" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_698fdd02-ea1b-4b24-a8b8-05689a1a4a9a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e3fb7d98-38ee-4692-a66d-39d9a4a196d9" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_698fdd02-ea1b-4b24-a8b8-05689a1a4a9a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_698fdd02-ea1b-4b24-a8b8-05689a1a4a9a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_698fdd02-ea1b-4b24-a8b8-05689a1a4a9a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_698fdd02-ea1b-4b24-a8b8-05689a1a4a9a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_5537e7ac-0091-464e-b9a5-cc812a1c323e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_698fdd02-ea1b-4b24-a8b8-05689a1a4a9a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_5537e7ac-0091-464e-b9a5-cc812a1c323e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_01af5eaf-ac17-4383-9bce-c31041a6cc05" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5537e7ac-0091-464e-b9a5-cc812a1c323e" xlink:to="loc_us-gaap_SeniorNotesMember_01af5eaf-ac17-4383-9bce-c31041a6cc05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_24ef8b10-4321-4dff-8960-8708bcb370b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5537e7ac-0091-464e-b9a5-cc812a1c323e" xlink:to="loc_us-gaap_SecuredDebtMember_24ef8b10-4321-4dff-8960-8708bcb370b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_db2f1fd9-fec4-495c-9640-2c5d7b1da0ae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e3fb7d98-38ee-4692-a66d-39d9a4a196d9" xlink:to="loc_us-gaap_VariableRateAxis_db2f1fd9-fec4-495c-9640-2c5d7b1da0ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_db2f1fd9-fec4-495c-9640-2c5d7b1da0ae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_db2f1fd9-fec4-495c-9640-2c5d7b1da0ae" xlink:to="loc_us-gaap_VariableRateDomain_db2f1fd9-fec4-495c-9640-2c5d7b1da0ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_db46d44f-c044-444f-b861-7c4cf6766bcd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_db2f1fd9-fec4-495c-9640-2c5d7b1da0ae" xlink:to="loc_us-gaap_VariableRateDomain_db46d44f-c044-444f-b861-7c4cf6766bcd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_fac28ea7-44d7-441a-8dc5-395e031c0e28" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_db46d44f-c044-444f-b861-7c4cf6766bcd" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_fac28ea7-44d7-441a-8dc5-395e031c0e28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_4be1ae89-350b-4843-85e6-3f3c4eec806f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_db46d44f-c044-444f-b861-7c4cf6766bcd" xlink:to="loc_us-gaap_BaseRateMember_4be1ae89-350b-4843-85e6-3f3c4eec806f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fbb83b00-e75d-4100-84a4-bb653a759878" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e3fb7d98-38ee-4692-a66d-39d9a4a196d9" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fbb83b00-e75d-4100-84a4-bb653a759878" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fbb83b00-e75d-4100-84a4-bb653a759878_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fbb83b00-e75d-4100-84a4-bb653a759878" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fbb83b00-e75d-4100-84a4-bb653a759878_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_74c43576-e1d9-49b9-9943-9067c94ec04d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fbb83b00-e75d-4100-84a4-bb653a759878" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_74c43576-e1d9-49b9-9943-9067c94ec04d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_ee6c9653-dbcb-40e4-aba5-ef4e8dc3fabf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_74c43576-e1d9-49b9-9943-9067c94ec04d" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_ee6c9653-dbcb-40e4-aba5-ef4e8dc3fabf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_b28ebd68-ebaa-4030-b0ae-add485711fc1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_74c43576-e1d9-49b9-9943-9067c94ec04d" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_b28ebd68-ebaa-4030-b0ae-add485711fc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_75ddb97d-534f-4030-a6c0-32c97328f08e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e3fb7d98-38ee-4692-a66d-39d9a4a196d9" xlink:to="loc_srt_RangeAxis_75ddb97d-534f-4030-a6c0-32c97328f08e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_75ddb97d-534f-4030-a6c0-32c97328f08e_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_75ddb97d-534f-4030-a6c0-32c97328f08e" xlink:to="loc_srt_RangeMember_75ddb97d-534f-4030-a6c0-32c97328f08e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c14fbdde-1b60-4e6f-8acb-e8cd440ded43" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_75ddb97d-534f-4030-a6c0-32c97328f08e" xlink:to="loc_srt_RangeMember_c14fbdde-1b60-4e6f-8acb-e8cd440ded43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_574df261-0cb0-4a0a-84c7-dcfbbd1c07f5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c14fbdde-1b60-4e6f-8acb-e8cd440ded43" xlink:to="loc_srt_MaximumMember_574df261-0cb0-4a0a-84c7-dcfbbd1c07f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_ef2e417c-0388-46ab-8869-14c41ebef900" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e3fb7d98-38ee-4692-a66d-39d9a4a196d9" xlink:to="loc_srt_LitigationCaseAxis_ef2e417c-0388-46ab-8869-14c41ebef900" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_ef2e417c-0388-46ab-8869-14c41ebef900_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_ef2e417c-0388-46ab-8869-14c41ebef900" xlink:to="loc_srt_LitigationCaseTypeDomain_ef2e417c-0388-46ab-8869-14c41ebef900_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_3e2f46ab-f57e-4a60-90c2-9bd0f2dab3e2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_ef2e417c-0388-46ab-8869-14c41ebef900" xlink:to="loc_srt_LitigationCaseTypeDomain_3e2f46ab-f57e-4a60-90c2-9bd0f2dab3e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationIllinoisMember_abd7a60f-3011-44eb-bcce-29200a8d4ad0" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationIllinoisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_3e2f46ab-f57e-4a60-90c2-9bd0f2dab3e2" xlink:to="loc_shc_EthyleneOxideTortLitigationIllinoisMember_abd7a60f-3011-44eb-bcce-29200a8d4ad0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_67d7c33d-fc8b-4e06-80e8-97e79a11a777" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e3fb7d98-38ee-4692-a66d-39d9a4a196d9" xlink:to="loc_us-gaap_LitigationStatusAxis_67d7c33d-fc8b-4e06-80e8-97e79a11a777" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_67d7c33d-fc8b-4e06-80e8-97e79a11a777_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_67d7c33d-fc8b-4e06-80e8-97e79a11a777" xlink:to="loc_us-gaap_LitigationStatusDomain_67d7c33d-fc8b-4e06-80e8-97e79a11a777_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_4d76d44f-412c-4804-8f85-1b87e55752bb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_67d7c33d-fc8b-4e06-80e8-97e79a11a777" xlink:to="loc_us-gaap_LitigationStatusDomain_4d76d44f-412c-4804-8f85-1b87e55752bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_634223db-bd5c-457d-9052-1d18f81878cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_4d76d44f-412c-4804-8f85-1b87e55752bb" xlink:to="loc_us-gaap_PendingLitigationMember_634223db-bd5c-457d-9052-1d18f81878cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_0d6da62e-e29d-44d3-bded-12ddbbe2bb02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_0d6da62e-e29d-44d3-bded-12ddbbe2bb02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_a15975e0-4aab-4735-9b12-ef2a5da96650" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_a15975e0-4aab-4735-9b12-ef2a5da96650" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DebtInstrumentApplicableFloorInterestRate_ce3eec5e-4342-4c07-9908-09393f698072" xlink:href="shc-20241231.xsd#shc_DebtInstrumentApplicableFloorInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_shc_DebtInstrumentApplicableFloorInterestRate_ce3eec5e-4342-4c07-9908-09393f698072" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DebtInstrumentPricingStepDownPercent_4c636301-517b-4698-aa39-9a547c0383d7" xlink:href="shc-20241231.xsd#shc_DebtInstrumentPricingStepDownPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_shc_DebtInstrumentPricingStepDownPercent_4c636301-517b-4698-aa39-9a547c0383d7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DebtInstrumentCovenantLeverageRatio_1c8cc8d6-6a94-4b51-a192-5bb28fb1a0ef" xlink:href="shc-20241231.xsd#shc_DebtInstrumentCovenantLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_shc_DebtInstrumentCovenantLeverageRatio_1c8cc8d6-6a94-4b51-a192-5bb28fb1a0ef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DebtInstrumentSoftCallPremiumPercent_2d847916-9d46-4b1d-b5a5-256fc5ec841d" xlink:href="shc-20241231.xsd#shc_DebtInstrumentSoftCallPremiumPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_shc_DebtInstrumentSoftCallPremiumPercent_2d847916-9d46-4b1d-b5a5-256fc5ec841d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_d8e7a040-0261-431c-9226-0e49107d0471" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_d8e7a040-0261-431c-9226-0e49107d0471" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_9c3b8d17-98ec-4616-b592-64db81816e2c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_9c3b8d17-98ec-4616-b592-64db81816e2c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_4fa37421-d338-42dc-9a15-c2d3688b8cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_4fa37421-d338-42dc-9a15-c2d3688b8cc7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_2a01006a-116e-4999-9f9f-717e8e608d4a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_2a01006a-116e-4999-9f9f-717e8e608d4a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_19529854-b30e-411b-af79-fcffe739cdcf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_19529854-b30e-411b-af79-fcffe739cdcf" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DebtInstrumentRedemptionPricePercentageProceedsFromEquityOfferings_72180aea-4703-44a2-a1ae-c9c0b56d6e2b" xlink:href="shc-20241231.xsd#shc_DebtInstrumentRedemptionPricePercentageProceedsFromEquityOfferings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_shc_DebtInstrumentRedemptionPricePercentageProceedsFromEquityOfferings_72180aea-4703-44a2-a1ae-c9c0b56d6e2b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DebtInstrumentRedemptionAsPercentOfOutstandingPrincipalAmount_f29153a8-096d-4335-9751-5ae5b5fae50b" xlink:href="shc-20241231.xsd#shc_DebtInstrumentRedemptionAsPercentOfOutstandingPrincipalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_shc_DebtInstrumentRedemptionAsPercentOfOutstandingPrincipalAmount_f29153a8-096d-4335-9751-5ae5b5fae50b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_cf85977b-c2de-4b0a-a53f-5cf5a736af13" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_cf85977b-c2de-4b0a-a53f-5cf5a736af13" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DebtInstrumentBaseAmountForDefault_e1284be5-fbce-4270-9c21-c5fe55faee77" xlink:href="shc-20241231.xsd#shc_DebtInstrumentBaseAmountForDefault"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_shc_DebtInstrumentBaseAmountForDefault_e1284be5-fbce-4270-9c21-c5fe55faee77" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DebtInstrumentBasisSpreadAdjustmentOnVariableRate_e4e3c783-cfbd-43fb-b7c2-5eab20c18a13" xlink:href="shc-20241231.xsd#shc_DebtInstrumentBasisSpreadAdjustmentOnVariableRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_shc_DebtInstrumentBasisSpreadAdjustmentOnVariableRate_e4e3c783-cfbd-43fb-b7c2-5eab20c18a13" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DebtInstrumentTriggeringPeriodForDefault_e52901c1-0462-48ff-a1e4-692a8a96872f" xlink:href="shc-20241231.xsd#shc_DebtInstrumentTriggeringPeriodForDefault"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_shc_DebtInstrumentTriggeringPeriodForDefault_e52901c1-0462-48ff-a1e4-692a8a96872f" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_653f79ca-2bab-49ab-8a55-40e52413c223" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_653f79ca-2bab-49ab-8a55-40e52413c223" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_e9236b96-9844-4c65-b5d4-9564c5b7286c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c68505e1-5acb-42fa-9885-0f8bfecf1075" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_e9236b96-9844-4c65-b5d4-9564c5b7286c" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#IncomeTaxesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_925ee836-d8fa-4fe3-8067-ae30d28283ec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_6c1de10d-27b1-4240-8741-9cdee27c87bb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_925ee836-d8fa-4fe3-8067-ae30d28283ec" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_6c1de10d-27b1-4240-8741-9cdee27c87bb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_e2011b9e-f957-4550-a0f9-dc57865046bb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_6c1de10d-27b1-4240-8741-9cdee27c87bb" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_e2011b9e-f957-4550-a0f9-dc57865046bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_e2011b9e-f957-4550-a0f9-dc57865046bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_e2011b9e-f957-4550-a0f9-dc57865046bb" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_e2011b9e-f957-4550-a0f9-dc57865046bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_c18f6faf-9f34-4773-b653-3655827bb547" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_e2011b9e-f957-4550-a0f9-dc57865046bb" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_c18f6faf-9f34-4773-b653-3655827bb547" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_de81d3a1-72fd-416f-8ea1-bca99172c4d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_c18f6faf-9f34-4773-b653-3655827bb547" xlink:to="loc_us-gaap_DomesticCountryMember_de81d3a1-72fd-416f-8ea1-bca99172c4d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_127fb4f9-27d8-473c-b709-e9536263fac7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_c18f6faf-9f34-4773-b653-3655827bb547" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_127fb4f9-27d8-473c-b709-e9536263fac7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_a4368d1b-21c6-4e03-bc57-3216d063f3e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_c18f6faf-9f34-4773-b653-3655827bb547" xlink:to="loc_us-gaap_ForeignCountryMember_a4368d1b-21c6-4e03-bc57-3216d063f3e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_56749839-a6ca-427e-a2f6-24958e49cf28" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_925ee836-d8fa-4fe3-8067-ae30d28283ec" xlink:to="loc_us-gaap_OperatingLossCarryforwards_56749839-a6ca-427e-a2f6-24958e49cf28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_265d3cd5-93e4-4fb2-a626-b1355a46454e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_925ee836-d8fa-4fe3-8067-ae30d28283ec" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_265d3cd5-93e4-4fb2-a626-b1355a46454e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsValuationAllowance_41db9669-6551-4da2-b1e9-d94006c25b5f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLossCarryforwardsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_925ee836-d8fa-4fe3-8067-ae30d28283ec" xlink:to="loc_us-gaap_OperatingLossCarryforwardsValuationAllowance_41db9669-6551-4da2-b1e9-d94006c25b5f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_c8c9fcec-7044-4a02-817d-7b3aca487424" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_925ee836-d8fa-4fe3-8067-ae30d28283ec" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_c8c9fcec-7044-4a02-817d-7b3aca487424" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_UnrecognizedTaxBenefitsGrossReserve_6646cbd9-b9a4-4378-a7e7-f763f915dcb0" xlink:href="shc-20241231.xsd#shc_UnrecognizedTaxBenefitsGrossReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_925ee836-d8fa-4fe3-8067-ae30d28283ec" xlink:to="loc_shc_UnrecognizedTaxBenefitsGrossReserve_6646cbd9-b9a4-4378-a7e7-f763f915dcb0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_IncomeTaxHolidayIncomeTaxBenefit_b6e3f4c7-8f1c-4ce7-8893-20c178c949f7" xlink:href="shc-20241231.xsd#shc_IncomeTaxHolidayIncomeTaxBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_925ee836-d8fa-4fe3-8067-ae30d28283ec" xlink:to="loc_shc_IncomeTaxHolidayIncomeTaxBenefit_b6e3f4c7-8f1c-4ce7-8893-20c178c949f7" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/EmployeeBenefitsAdditionalInformationDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#EmployeeBenefitsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/EmployeeBenefitsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e7f489ef-a8a1-438f-bcdc-9c96d656f4b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_d8adaf05-4b71-421a-b7c5-a6c619fcabfd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e7f489ef-a8a1-438f-bcdc-9c96d656f4b3" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_d8adaf05-4b71-421a-b7c5-a6c619fcabfd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationAxis_2b7338d6-31d2-42b0-9724-bd2fff15cdaf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanSponsorLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_d8adaf05-4b71-421a-b7c5-a6c619fcabfd" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationAxis_2b7338d6-31d2-42b0-9724-bd2fff15cdaf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_2b7338d6-31d2-42b0-9724-bd2fff15cdaf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_2b7338d6-31d2-42b0-9724-bd2fff15cdaf" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_2b7338d6-31d2-42b0-9724-bd2fff15cdaf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_3a524444-ea2d-4d92-9f98-b884d7e9131d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_2b7338d6-31d2-42b0-9724-bd2fff15cdaf" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_3a524444-ea2d-4d92-9f98-b884d7e9131d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticPlanMember_4912dce6-78a4-4c88-b813-b9df2c0ddea1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DomesticPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_3a524444-ea2d-4d92-9f98-b884d7e9131d" xlink:to="loc_us-gaap_DomesticPlanMember_4912dce6-78a4-4c88-b813-b9df2c0ddea1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_cce4c175-be07-4495-8b21-73f1084b9e23" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DomesticPlanMember_4912dce6-78a4-4c88-b813-b9df2c0ddea1" xlink:to="loc_country_US_cce4c175-be07-4495-8b21-73f1084b9e23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignPlanMember_cd1349b8-4c0a-41b4-8460-231968ff46fc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_3a524444-ea2d-4d92-9f98-b884d7e9131d" xlink:to="loc_us-gaap_ForeignPlanMember_cd1349b8-4c0a-41b4-8460-231968ff46fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_0ee712c0-6a29-4f35-a94d-19787c049263" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_d8adaf05-4b71-421a-b7c5-a6c619fcabfd" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_0ee712c0-6a29-4f35-a94d-19787c049263" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_0ee712c0-6a29-4f35-a94d-19787c049263_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_0ee712c0-6a29-4f35-a94d-19787c049263" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_0ee712c0-6a29-4f35-a94d-19787c049263_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_5275d10e-9aaf-4113-b280-e3b4f892d789" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_0ee712c0-6a29-4f35-a94d-19787c049263" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_5275d10e-9aaf-4113-b280-e3b4f892d789" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_ae74a37c-b09c-4e25-bd38-c627ad83a576" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_5275d10e-9aaf-4113-b280-e3b4f892d789" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_ae74a37c-b09c-4e25-bd38-c627ad83a576" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_3cc86be4-c185-48be-8ed0-103a24a63ba0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_d8adaf05-4b71-421a-b7c5-a6c619fcabfd" xlink:to="loc_srt_RangeAxis_3cc86be4-c185-48be-8ed0-103a24a63ba0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_3cc86be4-c185-48be-8ed0-103a24a63ba0_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_3cc86be4-c185-48be-8ed0-103a24a63ba0" xlink:to="loc_srt_RangeMember_3cc86be4-c185-48be-8ed0-103a24a63ba0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ee02c048-baf4-46c9-8cde-0b78a2e7208b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_3cc86be4-c185-48be-8ed0-103a24a63ba0" xlink:to="loc_srt_RangeMember_ee02c048-baf4-46c9-8cde-0b78a2e7208b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_9b753e44-9c30-4fd6-8205-d53a33615d34" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ee02c048-baf4-46c9-8cde-0b78a2e7208b" xlink:to="loc_srt_MaximumMember_9b753e44-9c30-4fd6-8205-d53a33615d34" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_88c20586-c430-4797-bec1-c8eef4557542" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e7f489ef-a8a1-438f-bcdc-9c96d656f4b3" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_88c20586-c430-4797-bec1-c8eef4557542" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LettersOfCreditSolvencyPaymentAsPercentOfMarketValue_3e3aa1e5-c957-45f1-a34a-2bfc162b9e50" xlink:href="shc-20241231.xsd#shc_LettersOfCreditSolvencyPaymentAsPercentOfMarketValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e7f489ef-a8a1-438f-bcdc-9c96d656f4b3" xlink:to="loc_shc_LettersOfCreditSolvencyPaymentAsPercentOfMarketValue_3e3aa1e5-c957-45f1-a34a-2bfc162b9e50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_a514e4c6-b456-4db6-88f7-bd384a946ea0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e7f489ef-a8a1-438f-bcdc-9c96d656f4b3" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_a514e4c6-b456-4db6-88f7-bd384a946ea0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PeriodOfActualFundingRequirements_bab6babb-6d30-4712-a9e6-6fb801a42c8b" xlink:href="shc-20241231.xsd#shc_PeriodOfActualFundingRequirements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e7f489ef-a8a1-438f-bcdc-9c96d656f4b3" xlink:to="loc_shc_PeriodOfActualFundingRequirements_bab6babb-6d30-4712-a9e6-6fb801a42c8b" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/EmployeeBenefitsScheduleofNetPeriodicBenefitCostDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#EmployeeBenefitsScheduleofNetPeriodicBenefitCostDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/EmployeeBenefitsScheduleofNetPeriodicBenefitCostDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39abbd46-45c9-459e-885d-f4c773bfa77c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_200f5e16-76f3-4027-b268-c5e4fd6d7da4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39abbd46-45c9-459e-885d-f4c773bfa77c" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_200f5e16-76f3-4027-b268-c5e4fd6d7da4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_6e429943-2faa-4109-9d82-fca27a350ad0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_200f5e16-76f3-4027-b268-c5e4fd6d7da4" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_6e429943-2faa-4109-9d82-fca27a350ad0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_6e429943-2faa-4109-9d82-fca27a350ad0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_6e429943-2faa-4109-9d82-fca27a350ad0" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_6e429943-2faa-4109-9d82-fca27a350ad0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_78e487ee-ab9b-4e85-90f7-d838e9f3e53e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_6e429943-2faa-4109-9d82-fca27a350ad0" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_78e487ee-ab9b-4e85-90f7-d838e9f3e53e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_bd6d8181-f95a-4de3-b3ff-d14cd2abf653" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_78e487ee-ab9b-4e85-90f7-d838e9f3e53e" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_bd6d8181-f95a-4de3-b3ff-d14cd2abf653" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_042d5c21-49b1-405e-9830-cb547ab9ef77" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_78e487ee-ab9b-4e85-90f7-d838e9f3e53e" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_042d5c21-49b1-405e-9830-cb547ab9ef77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_2ac303f5-deb8-4826-8dd1-eb6630c69abd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39abbd46-45c9-459e-885d-f4c773bfa77c" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_2ac303f5-deb8-4826-8dd1-eb6630c69abd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DefinedBenefitPlanServiceCost1_15b1a106-0a91-48bb-8a38-34e12d7ce4e2" xlink:href="shc-20241231.xsd#shc_DefinedBenefitPlanServiceCost1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39abbd46-45c9-459e-885d-f4c773bfa77c" xlink:to="loc_shc_DefinedBenefitPlanServiceCost1_15b1a106-0a91-48bb-8a38-34e12d7ce4e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_1dbf0182-15be-491a-9ad4-53122ee41730" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39abbd46-45c9-459e-885d-f4c773bfa77c" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_1dbf0182-15be-491a-9ad4-53122ee41730" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_a4cb2044-a27d-46c8-b4bd-de8090b37190" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39abbd46-45c9-459e-885d-f4c773bfa77c" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_a4cb2044-a27d-46c8-b4bd-de8090b37190" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_219679de-a9a3-48ee-9623-0fa6c986adc0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39abbd46-45c9-459e-885d-f4c773bfa77c" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_219679de-a9a3-48ee-9623-0fa6c986adc0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_efbd274e-2e75-4fca-8533-dd822f6c41ae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39abbd46-45c9-459e-885d-f4c773bfa77c" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_efbd274e-2e75-4fca-8533-dd822f6c41ae" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/EmployeeBenefitsScheduleofWeightedAverageAssumptionsUsedintheMeasurementofBenefitObligationDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#EmployeeBenefitsScheduleofWeightedAverageAssumptionsUsedintheMeasurementofBenefitObligationDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/EmployeeBenefitsScheduleofWeightedAverageAssumptionsUsedintheMeasurementofBenefitObligationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3282b50d-64b1-42be-8209-54a1d555053e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b148dc2b-7c3d-44d1-8c7f-fc171a0a6196" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3282b50d-64b1-42be-8209-54a1d555053e" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b148dc2b-7c3d-44d1-8c7f-fc171a0a6196" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_1d073d0e-64a0-49af-9d59-ae2770a0b0c5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b148dc2b-7c3d-44d1-8c7f-fc171a0a6196" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_1d073d0e-64a0-49af-9d59-ae2770a0b0c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_1d073d0e-64a0-49af-9d59-ae2770a0b0c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_1d073d0e-64a0-49af-9d59-ae2770a0b0c5" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_1d073d0e-64a0-49af-9d59-ae2770a0b0c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_7c4bddd1-fb47-447b-93ef-d8cadc568b02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_1d073d0e-64a0-49af-9d59-ae2770a0b0c5" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_7c4bddd1-fb47-447b-93ef-d8cadc568b02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_b2c301b2-cf0d-4d4b-a35a-e0d7865e1caf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_7c4bddd1-fb47-447b-93ef-d8cadc568b02" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_b2c301b2-cf0d-4d4b-a35a-e0d7865e1caf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_63baf1b3-b262-4e13-86c8-1417ce262a4b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_7c4bddd1-fb47-447b-93ef-d8cadc568b02" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_63baf1b3-b262-4e13-86c8-1417ce262a4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_11b14a22-4bea-4a3d-901a-2bfaf11e6511" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3282b50d-64b1-42be-8209-54a1d555053e" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_11b14a22-4bea-4a3d-901a-2bfaf11e6511" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_0953af1f-fd84-417f-b573-7f66303ce1d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_11b14a22-4bea-4a3d-901a-2bfaf11e6511" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_0953af1f-fd84-417f-b573-7f66303ce1d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease_b589c9b5-51e5-4e30-a99c-68f6bf8d1b90" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_11b14a22-4bea-4a3d-901a-2bfaf11e6511" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease_b589c9b5-51e5-4e30-a99c-68f6bf8d1b90" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear_b10aad34-7c19-4dc2-a3d1-8d05319ea5f2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_11b14a22-4bea-4a3d-901a-2bfaf11e6511" xlink:to="loc_us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear_b10aad34-7c19-4dc2-a3d1-8d05319ea5f2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1_d6b5efc5-f994-48e6-b921-a46cd1c14f1b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_11b14a22-4bea-4a3d-901a-2bfaf11e6511" xlink:to="loc_us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1_d6b5efc5-f994-48e6-b921-a46cd1c14f1b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DefinedBenefitPlanPeriodHealthCareCostTrendRateReachesUltimateTrendRate_129da012-db17-4423-9469-cde969145cb2" xlink:href="shc-20241231.xsd#shc_DefinedBenefitPlanPeriodHealthCareCostTrendRateReachesUltimateTrendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_11b14a22-4bea-4a3d-901a-2bfaf11e6511" xlink:to="loc_shc_DefinedBenefitPlanPeriodHealthCareCostTrendRateReachesUltimateTrendRate_129da012-db17-4423-9469-cde969145cb2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_baaa0f66-f4c3-4656-b5ce-184a315c7afd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3282b50d-64b1-42be-8209-54a1d555053e" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_baaa0f66-f4c3-4656-b5ce-184a315c7afd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_eaea795f-4c39-42f0-8f89-0109b30c7f2e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_baaa0f66-f4c3-4656-b5ce-184a315c7afd" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_eaea795f-4c39-42f0-8f89-0109b30c7f2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_fea22228-6e97-4731-9bb6-cd584a517671" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_baaa0f66-f4c3-4656-b5ce-184a315c7afd" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_fea22228-6e97-4731-9bb6-cd584a517671" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease_691b026d-0cf9-4f79-9d22-71ec60d7b4af" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_baaa0f66-f4c3-4656-b5ce-184a315c7afd" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease_691b026d-0cf9-4f79-9d22-71ec60d7b4af" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/EmployeeBenefitsScheduleofReconciliationofChangesinBenefitObligationsandFairValueofPlanAssetsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#EmployeeBenefitsScheduleofReconciliationofChangesinBenefitObligationsandFairValueofPlanAssetsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/EmployeeBenefitsScheduleofReconciliationofChangesinBenefitObligationsandFairValueofPlanAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_dfae8670-c6b9-4e64-abb9-c1fdb196b403" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b991a266-e54d-49c6-8993-86e37c442190" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_dfae8670-c6b9-4e64-abb9-c1fdb196b403" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b991a266-e54d-49c6-8993-86e37c442190" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_9e5613c8-fddf-4e34-8b6b-ff77ca26de81" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b991a266-e54d-49c6-8993-86e37c442190" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_9e5613c8-fddf-4e34-8b6b-ff77ca26de81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_9e5613c8-fddf-4e34-8b6b-ff77ca26de81_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_9e5613c8-fddf-4e34-8b6b-ff77ca26de81" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_9e5613c8-fddf-4e34-8b6b-ff77ca26de81_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_fba8916b-5040-4868-ac51-28a8719c302b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_9e5613c8-fddf-4e34-8b6b-ff77ca26de81" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_fba8916b-5040-4868-ac51-28a8719c302b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_28dabbbc-a72d-4a07-ba5c-d13c6f4b32ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_fba8916b-5040-4868-ac51-28a8719c302b" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_28dabbbc-a72d-4a07-ba5c-d13c6f4b32ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_0c6a5d50-e11e-4225-8800-7975cd735703" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_fba8916b-5040-4868-ac51-28a8719c302b" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_0c6a5d50-e11e-4225-8800-7975cd735703" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_203e0a24-5f8a-475d-a175-6abd09c8864e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_dfae8670-c6b9-4e64-abb9-c1fdb196b403" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_203e0a24-5f8a-475d-a175-6abd09c8864e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_3bf4a65a-5cda-4989-aea7-e2039047051b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_203e0a24-5f8a-475d-a175-6abd09c8864e" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_3bf4a65a-5cda-4989-aea7-e2039047051b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_b2f3f519-5a29-4d5b-bd90-a64a18d88c1d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_203e0a24-5f8a-475d-a175-6abd09c8864e" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_b2f3f519-5a29-4d5b-bd90-a64a18d88c1d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_76b8ae73-f152-49df-81a4-868f2f303daa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_203e0a24-5f8a-475d-a175-6abd09c8864e" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_76b8ae73-f152-49df-81a4-868f2f303daa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_beee8706-693f-4c96-ba2e-6a71fadabbd7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_203e0a24-5f8a-475d-a175-6abd09c8864e" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_beee8706-693f-4c96-ba2e-6a71fadabbd7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_5bc16a25-4ee0-4ca3-879c-7ca4086f8c37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_203e0a24-5f8a-475d-a175-6abd09c8864e" xlink:to="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_5bc16a25-4ee0-4ca3-879c-7ca4086f8c37" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_889a9c4b-6c73-4b5c-9d66-619a0e9de5a3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_203e0a24-5f8a-475d-a175-6abd09c8864e" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_889a9c4b-6c73-4b5c-9d66-619a0e9de5a3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_84b266f4-2959-49a7-b3d2-64bb27029c13" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_203e0a24-5f8a-475d-a175-6abd09c8864e" xlink:to="loc_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_84b266f4-2959-49a7-b3d2-64bb27029c13" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_e0650cb7-2b22-4674-ad5f-db40038e66aa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_704097e7-c2f2-42ad-8a53-f3c5d974370d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_dfae8670-c6b9-4e64-abb9-c1fdb196b403" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_704097e7-c2f2-42ad-8a53-f3c5d974370d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_c1dc6431-8cd6-4b42-84f7-5c17c57d0474" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_704097e7-c2f2-42ad-8a53-f3c5d974370d" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_c1dc6431-8cd6-4b42-84f7-5c17c57d0474" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_665d6261-8b50-4cf4-818f-5ca18ce8a28d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_704097e7-c2f2-42ad-8a53-f3c5d974370d" xlink:to="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_665d6261-8b50-4cf4-818f-5ca18ce8a28d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_fa23036a-3a57-4788-ad1e-bb207f55a79c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_704097e7-c2f2-42ad-8a53-f3c5d974370d" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_fa23036a-3a57-4788-ad1e-bb207f55a79c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_446c7b7b-5e17-467b-9619-41c94faf62fb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_704097e7-c2f2-42ad-8a53-f3c5d974370d" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_446c7b7b-5e17-467b-9619-41c94faf62fb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant_e215c746-2aa4-434a-ab1f-0714e9fa7fbf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_704097e7-c2f2-42ad-8a53-f3c5d974370d" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant_e215c746-2aa4-434a-ab1f-0714e9fa7fbf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_b977de18-2d52-47be-9a1d-23ebb310e09f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_704097e7-c2f2-42ad-8a53-f3c5d974370d" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_b977de18-2d52-47be-9a1d-23ebb310e09f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_2f903182-8992-47ed-ba9d-031a279ef6b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_3d0d7dc2-7654-4e42-8556-ecffc8d749c8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_dfae8670-c6b9-4e64-abb9-c1fdb196b403" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_3d0d7dc2-7654-4e42-8556-ecffc8d749c8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation_1e17c73d-ac48-449b-a425-71a9ead8181e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_dfae8670-c6b9-4e64-abb9-c1fdb196b403" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation_1e17c73d-ac48-449b-a425-71a9ead8181e" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/EmployeeBenefitsScheduleofReconciliationofFundedStatusDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#EmployeeBenefitsScheduleofReconciliationofFundedStatusDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/EmployeeBenefitsScheduleofReconciliationofFundedStatusDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_28a9849f-156d-4d06-8760-e3d16b2c5b33" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_646615eb-ea9a-4c1b-849f-87a276680794" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_28a9849f-156d-4d06-8760-e3d16b2c5b33" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_646615eb-ea9a-4c1b-849f-87a276680794" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_8c38c1b8-c038-4078-842f-e1a89b73fb28" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_646615eb-ea9a-4c1b-849f-87a276680794" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_8c38c1b8-c038-4078-842f-e1a89b73fb28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_8c38c1b8-c038-4078-842f-e1a89b73fb28_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_8c38c1b8-c038-4078-842f-e1a89b73fb28" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_8c38c1b8-c038-4078-842f-e1a89b73fb28_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_02859e48-b239-41e0-b962-87078ff0c8fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_8c38c1b8-c038-4078-842f-e1a89b73fb28" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_02859e48-b239-41e0-b962-87078ff0c8fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_9f14609a-e82a-408e-8443-c98ee902d344" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_02859e48-b239-41e0-b962-87078ff0c8fa" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_9f14609a-e82a-408e-8443-c98ee902d344" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_8d20c8c0-7c02-4440-a469-72881b55133c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_02859e48-b239-41e0-b962-87078ff0c8fa" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_8d20c8c0-7c02-4440-a469-72881b55133c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation_ae3af225-0797-472a-b9ad-dbe7810ac2ec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_28a9849f-156d-4d06-8760-e3d16b2c5b33" xlink:to="loc_us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation_ae3af225-0797-472a-b9ad-dbe7810ac2ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsLiabilitiesProjectedBenefitObligation_adfe8127-35b3-40fb-a9a7-c86a0a94f1be" xlink:href="shc-20241231.xsd#shc_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsLiabilitiesProjectedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_28a9849f-156d-4d06-8760-e3d16b2c5b33" xlink:to="loc_shc_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsLiabilitiesProjectedBenefitObligation_adfe8127-35b3-40fb-a9a7-c86a0a94f1be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DefinedBenefitPlanPlanAssetsFairValue_f3427e7a-1bb1-4976-83d6-bd28b7836cc3" xlink:href="shc-20241231.xsd#shc_DefinedBenefitPlanPlanAssetsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_28a9849f-156d-4d06-8760-e3d16b2c5b33" xlink:to="loc_shc_DefinedBenefitPlanPlanAssetsFairValue_f3427e7a-1bb1-4976-83d6-bd28b7836cc3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsPlanAssetsLiabilities_1cbd09f7-cf3e-4780-8e63-ec2784485756" xlink:href="shc-20241231.xsd#shc_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsPlanAssetsLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_28a9849f-156d-4d06-8760-e3d16b2c5b33" xlink:to="loc_shc_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsPlanAssetsLiabilities_1cbd09f7-cf3e-4780-8e63-ec2784485756" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DefinedBenefitPlanBenefitObligationUnrecognizedActuarialGainLoss_6cc0933f-16e3-45a7-8aa9-46ba6dbf025b" xlink:href="shc-20241231.xsd#shc_DefinedBenefitPlanBenefitObligationUnrecognizedActuarialGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_28a9849f-156d-4d06-8760-e3d16b2c5b33" xlink:to="loc_shc_DefinedBenefitPlanBenefitObligationUnrecognizedActuarialGainLoss_6cc0933f-16e3-45a7-8aa9-46ba6dbf025b" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/EmployeeBenefitsScheduleofAmountsinAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#EmployeeBenefitsScheduleofAmountsinAccumulatedOtherComprehensiveIncomeLossDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/EmployeeBenefitsScheduleofAmountsinAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_57f0ab17-1e0e-4706-87bc-ac897ac11dee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5d364801-4a13-42ed-9388-439a62f15a76" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_57f0ab17-1e0e-4706-87bc-ac897ac11dee" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5d364801-4a13-42ed-9388-439a62f15a76" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_a42cd688-17c5-45b7-8e66-ba53fa76eb6f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5d364801-4a13-42ed-9388-439a62f15a76" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_a42cd688-17c5-45b7-8e66-ba53fa76eb6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_a42cd688-17c5-45b7-8e66-ba53fa76eb6f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_a42cd688-17c5-45b7-8e66-ba53fa76eb6f" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_a42cd688-17c5-45b7-8e66-ba53fa76eb6f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_17c5cca3-4e79-4c89-936e-7465a917ac02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_a42cd688-17c5-45b7-8e66-ba53fa76eb6f" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_17c5cca3-4e79-4c89-936e-7465a917ac02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_11d93c44-b513-4003-af31-435153a69acc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_17c5cca3-4e79-4c89-936e-7465a917ac02" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_11d93c44-b513-4003-af31-435153a69acc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_9971ce70-292c-4952-ace0-08f9db7e5235" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_17c5cca3-4e79-4c89-936e-7465a917ac02" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_9971ce70-292c-4952-ace0-08f9db7e5235" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_cfd53f2e-1fd3-4db7-8322-53b5ad41d0d0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_57f0ab17-1e0e-4706-87bc-ac897ac11dee" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_cfd53f2e-1fd3-4db7-8322-53b5ad41d0d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeLossDeferredIncomeTax_5b7250c7-cadf-4421-bafb-72e2ce021c8d" xlink:href="shc-20241231.xsd#shc_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeLossDeferredIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_57f0ab17-1e0e-4706-87bc-ac897ac11dee" xlink:to="loc_shc_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeLossDeferredIncomeTax_5b7250c7-cadf-4421-bafb-72e2ce021c8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax_49666f79-f1dd-46f4-bea2-b49ed87f0370" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_57f0ab17-1e0e-4706-87bc-ac897ac11dee" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax_49666f79-f1dd-46f4-bea2-b49ed87f0370" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NetActuarialLossAmountExpectedToBeReclassifiedInTheNextTwelveMonthInAccumulatedOtherComprehensiveIncomeLoss_4f309710-9691-46e8-a5f3-a221adc2f04d" xlink:href="shc-20241231.xsd#shc_NetActuarialLossAmountExpectedToBeReclassifiedInTheNextTwelveMonthInAccumulatedOtherComprehensiveIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_57f0ab17-1e0e-4706-87bc-ac897ac11dee" xlink:to="loc_shc_NetActuarialLossAmountExpectedToBeReclassifiedInTheNextTwelveMonthInAccumulatedOtherComprehensiveIncomeLoss_4f309710-9691-46e8-a5f3-a221adc2f04d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/EmployeeBenefitsScheduleofPensionPlanWeightedAverageAssetAllocationsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#EmployeeBenefitsScheduleofPensionPlanWeightedAverageAssetAllocationsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/EmployeeBenefitsScheduleofPensionPlanWeightedAverageAssetAllocationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_b47fcdf5-d2c7-40a4-b36d-bad8528833b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_96d75d41-740b-439a-9c9e-49ca61c4b927" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_b47fcdf5-d2c7-40a4-b36d-bad8528833b2" xlink:to="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_96d75d41-740b-439a-9c9e-49ca61c4b927" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_ca92be29-b1da-410b-a6d1-bb287b3bd062" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_96d75d41-740b-439a-9c9e-49ca61c4b927" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_ca92be29-b1da-410b-a6d1-bb287b3bd062" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_ca92be29-b1da-410b-a6d1-bb287b3bd062_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_ca92be29-b1da-410b-a6d1-bb287b3bd062" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_ca92be29-b1da-410b-a6d1-bb287b3bd062_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_0371589f-78df-4667-9c2c-e272f365149b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_ca92be29-b1da-410b-a6d1-bb287b3bd062" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_0371589f-78df-4667-9c2c-e272f365149b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_d5fa2487-9f72-41f6-8c54-a417808bf314" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_0371589f-78df-4667-9c2c-e272f365149b" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_d5fa2487-9f72-41f6-8c54-a417808bf314" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_7b3a6337-7ba9-4895-8ae6-4cf30ee0b3aa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_0371589f-78df-4667-9c2c-e272f365149b" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_7b3a6337-7ba9-4895-8ae6-4cf30ee0b3aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_640d602e-d3bd-4f42-a908-fcda0f9b1474" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_96d75d41-740b-439a-9c9e-49ca61c4b927" xlink:to="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_640d602e-d3bd-4f42-a908-fcda0f9b1474" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_640d602e-d3bd-4f42-a908-fcda0f9b1474_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_640d602e-d3bd-4f42-a908-fcda0f9b1474" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_640d602e-d3bd-4f42-a908-fcda0f9b1474_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_81e8e37c-1d34-4740-8219-73ab5c7086be" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_640d602e-d3bd-4f42-a908-fcda0f9b1474" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_81e8e37c-1d34-4740-8219-73ab5c7086be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanCashMember_11e9c79a-fefe-40ae-a44e-06a93b8db177" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanCashMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_81e8e37c-1d34-4740-8219-73ab5c7086be" xlink:to="loc_us-gaap_DefinedBenefitPlanCashMember_11e9c79a-fefe-40ae-a44e-06a93b8db177" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDebtSecurityMember_d118bd9c-8506-4e85-b267-0839ba02ce54" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanDebtSecurityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_81e8e37c-1d34-4740-8219-73ab5c7086be" xlink:to="loc_us-gaap_DefinedBenefitPlanDebtSecurityMember_d118bd9c-8506-4e85-b267-0839ba02ce54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEquitySecuritiesMember_d1b86238-1153-48f5-bbab-1bfbc3075d61" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_81e8e37c-1d34-4740-8219-73ab5c7086be" xlink:to="loc_us-gaap_DefinedBenefitPlanEquitySecuritiesMember_d1b86238-1153-48f5-bbab-1bfbc3075d61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgeFundsMember_f48f23a6-5489-492a-b122-f300ede98401" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgeFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_81e8e37c-1d34-4740-8219-73ab5c7086be" xlink:to="loc_us-gaap_HedgeFundsMember_f48f23a6-5489-492a-b122-f300ede98401" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_2d77d52d-46be-4a14-86fe-0e1ffa3b4981" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_b47fcdf5-d2c7-40a4-b36d-bad8528833b2" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_2d77d52d-46be-4a14-86fe-0e1ffa3b4981" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations_86830307-dd6f-4320-9bac-2905ded642b7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_b47fcdf5-d2c7-40a4-b36d-bad8528833b2" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations_86830307-dd6f-4320-9bac-2905ded642b7" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/EmployeeBenefitsScheduleofExpectedFutureBenefitPaymentsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#EmployeeBenefitsScheduleofExpectedFutureBenefitPaymentsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/EmployeeBenefitsScheduleofExpectedFutureBenefitPaymentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_b7fdbe0b-5e0d-42b7-abda-ded0b65ade9c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0db6e27a-1129-4c3c-a89f-ee6bd98ee4eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_b7fdbe0b-5e0d-42b7-abda-ded0b65ade9c" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0db6e27a-1129-4c3c-a89f-ee6bd98ee4eb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_36fa385b-a122-4b7f-b8d2-c9cce35370ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0db6e27a-1129-4c3c-a89f-ee6bd98ee4eb" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_36fa385b-a122-4b7f-b8d2-c9cce35370ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_36fa385b-a122-4b7f-b8d2-c9cce35370ba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_36fa385b-a122-4b7f-b8d2-c9cce35370ba" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_36fa385b-a122-4b7f-b8d2-c9cce35370ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_8ef3b7f9-57ad-4ced-ae46-2e53eaa7f826" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_36fa385b-a122-4b7f-b8d2-c9cce35370ba" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_8ef3b7f9-57ad-4ced-ae46-2e53eaa7f826" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_8cbf1f07-330e-42b0-b754-bf2abe152c23" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_8ef3b7f9-57ad-4ced-ae46-2e53eaa7f826" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_8cbf1f07-330e-42b0-b754-bf2abe152c23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_8c5aeb1e-649d-4116-a131-3741f17b7afd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_8ef3b7f9-57ad-4ced-ae46-2e53eaa7f826" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_8c5aeb1e-649d-4116-a131-3741f17b7afd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_8a45f7c0-d29a-4632-bb1a-7e07441063ed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_b7fdbe0b-5e0d-42b7-abda-ded0b65ade9c" xlink:to="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_8a45f7c0-d29a-4632-bb1a-7e07441063ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_09f796a1-b78f-428b-b3fb-46122bd5e093" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_8a45f7c0-d29a-4632-bb1a-7e07441063ed" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_09f796a1-b78f-428b-b3fb-46122bd5e093" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_911f41f0-863f-4b45-9478-10d85876dc65" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_8a45f7c0-d29a-4632-bb1a-7e07441063ed" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_911f41f0-863f-4b45-9478-10d85876dc65" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_54c1451d-3195-4b67-8a43-d1dd3df86ff8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_8a45f7c0-d29a-4632-bb1a-7e07441063ed" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_54c1451d-3195-4b67-8a43-d1dd3df86ff8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_8756600e-58f0-465b-9741-b55ac37a709e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_8a45f7c0-d29a-4632-bb1a-7e07441063ed" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_8756600e-58f0-465b-9741-b55ac37a709e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_6bef4423-2467-4d56-8c3f-872e55869cdc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_8a45f7c0-d29a-4632-bb1a-7e07441063ed" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_6bef4423-2467-4d56-8c3f-872e55869cdc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_cc986c23-319f-49e8-9ae2-9f238c4e096c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_8a45f7c0-d29a-4632-bb1a-7e07441063ed" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_cc986c23-319f-49e8-9ae2-9f238c4e096c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DefinedBenefitPlanExpectedFutureBenefitPayment_2f7e4b9b-dfd4-471e-836c-b6c25ce29470" xlink:href="shc-20241231.xsd#shc_DefinedBenefitPlanExpectedFutureBenefitPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_8a45f7c0-d29a-4632-bb1a-7e07441063ed" xlink:to="loc_shc_DefinedBenefitPlanExpectedFutureBenefitPayment_2f7e4b9b-dfd4-471e-836c-b6c25ce29470" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/EmployeeBenefitsScheduleofaOnePercentagePointChangeinAssumedHealthCareCostTrendRatesDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#EmployeeBenefitsScheduleofaOnePercentagePointChangeinAssumedHealthCareCostTrendRatesDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/EmployeeBenefitsScheduleofaOnePercentagePointChangeinAssumedHealthCareCostTrendRatesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_eddd3309-1df8-40c5-96f6-f85e53654d68" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_58d47eb6-a064-4164-9ada-85a9707a8ae0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_eddd3309-1df8-40c5-96f6-f85e53654d68" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_58d47eb6-a064-4164-9ada-85a9707a8ae0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_3beaa4c2-5389-4280-97aa-a891d37c1eaf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_58d47eb6-a064-4164-9ada-85a9707a8ae0" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_3beaa4c2-5389-4280-97aa-a891d37c1eaf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_3beaa4c2-5389-4280-97aa-a891d37c1eaf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_3beaa4c2-5389-4280-97aa-a891d37c1eaf" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_3beaa4c2-5389-4280-97aa-a891d37c1eaf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_c6b34d45-cb16-49dc-abab-4ca95bfb1fcf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_3beaa4c2-5389-4280-97aa-a891d37c1eaf" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_c6b34d45-cb16-49dc-abab-4ca95bfb1fcf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_d52c4ad3-13ec-4c65-b6f3-b1afd8d847ae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_c6b34d45-cb16-49dc-abab-4ca95bfb1fcf" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_d52c4ad3-13ec-4c65-b6f3-b1afd8d847ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_0732a24c-a8de-4e2e-ace8-6e04f5b0e457" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_c6b34d45-cb16-49dc-abab-4ca95bfb1fcf" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_0732a24c-a8de-4e2e-ace8-6e04f5b0e457" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnServiceAndInterestCostComponents_bcc12fd0-54ca-40cc-90f5-9eca93d7ab81" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnServiceAndInterestCostComponents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_eddd3309-1df8-40c5-96f6-f85e53654d68" xlink:to="loc_us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnServiceAndInterestCostComponents_bcc12fd0-54ca-40cc-90f5-9eca93d7ab81" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents1_5a8f00c4-7263-4262-84c1-2eb33e176a2b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_eddd3309-1df8-40c5-96f6-f85e53654d68" xlink:to="loc_us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents1_5a8f00c4-7263-4262-84c1-2eb33e176a2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnAccumulatedPostretirementBenefitObligation_b03c2ee2-e095-40d8-97d8-681a0ee1c6e8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnAccumulatedPostretirementBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_eddd3309-1df8-40c5-96f6-f85e53654d68" xlink:to="loc_us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnAccumulatedPostretirementBenefitObligation_b03c2ee2-e095-40d8-97d8-681a0ee1c6e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation1_9f2939e5-cb53-4171-8b4b-f81007acaabd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_eddd3309-1df8-40c5-96f6-f85e53654d68" xlink:to="loc_us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation1_9f2939e5-cb53-4171-8b4b-f81007acaabd" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/OtherComprehensiveIncomeLossDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#OtherComprehensiveIncomeLossDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/OtherComprehensiveIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2ecae8d6-87fb-49af-beb5-7a9647c9a946" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_73a1a2bc-b6fe-4714-98a7-8f69cabc2626" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2ecae8d6-87fb-49af-beb5-7a9647c9a946" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_73a1a2bc-b6fe-4714-98a7-8f69cabc2626" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_63703f82-1b5f-47d1-aea6-42eb5c4fd032" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_73a1a2bc-b6fe-4714-98a7-8f69cabc2626" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_63703f82-1b5f-47d1-aea6-42eb5c4fd032" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_63703f82-1b5f-47d1-aea6-42eb5c4fd032_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_63703f82-1b5f-47d1-aea6-42eb5c4fd032" xlink:to="loc_us-gaap_EquityComponentDomain_63703f82-1b5f-47d1-aea6-42eb5c4fd032_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_6a672440-7c11-4064-8ed3-97c4a20bdcf5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_63703f82-1b5f-47d1-aea6-42eb5c4fd032" xlink:to="loc_us-gaap_EquityComponentDomain_6a672440-7c11-4064-8ed3-97c4a20bdcf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_8f5b63c2-1c19-4d5c-bb4a-7434f7c8f9dd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6a672440-7c11-4064-8ed3-97c4a20bdcf5" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_8f5b63c2-1c19-4d5c-bb4a-7434f7c8f9dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_ee6ce62b-4637-4bcd-a5d4-baf06be048ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6a672440-7c11-4064-8ed3-97c4a20bdcf5" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_ee6ce62b-4637-4bcd-a5d4-baf06be048ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_a65476f5-c265-4f66-9cca-7b7b51ab1656" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6a672440-7c11-4064-8ed3-97c4a20bdcf5" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_a65476f5-c265-4f66-9cca-7b7b51ab1656" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_66fe9959-ea70-4ec7-9522-47b6ecf36472" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6a672440-7c11-4064-8ed3-97c4a20bdcf5" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_66fe9959-ea70-4ec7-9522-47b6ecf36472" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_973f9733-999c-49fb-9f15-dd3b29f392f6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2ecae8d6-87fb-49af-beb5-7a9647c9a946" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_973f9733-999c-49fb-9f15-dd3b29f392f6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_28f8a535-f648-4f3b-b1c3-c413400976f7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2ecae8d6-87fb-49af-beb5-7a9647c9a946" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_28f8a535-f648-4f3b-b1c3-c413400976f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_07726696-6c8c-4712-a8fd-519028d79f16" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2ecae8d6-87fb-49af-beb5-7a9647c9a946" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_07726696-6c8c-4712-a8fd-519028d79f16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_8aa1f191-5fa7-4790-add0-9cdba8a4f3ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2ecae8d6-87fb-49af-beb5-7a9647c9a946" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_8aa1f191-5fa7-4790-add0-9cdba8a4f3ac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9ef469cb-6658-417c-a127-ade2bc5df3b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/ShareBasedCompensationAdditionalInformationDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#ShareBasedCompensationAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/ShareBasedCompensationAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27816b6d-c8b3-4ba6-87cc-c9f275f6ac0c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27816b6d-c8b3-4ba6-87cc-c9f275f6ac0c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_f3974c8d-bb29-4fc4-97d5-d0db8ea39810" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27816b6d-c8b3-4ba6-87cc-c9f275f6ac0c" xlink:to="loc_us-gaap_AwardTypeAxis_f3974c8d-bb29-4fc4-97d5-d0db8ea39810" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f3974c8d-bb29-4fc4-97d5-d0db8ea39810_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_f3974c8d-bb29-4fc4-97d5-d0db8ea39810" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f3974c8d-bb29-4fc4-97d5-d0db8ea39810_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f0b43901-b45c-478a-b1f8-0b57e4452806" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_f3974c8d-bb29-4fc4-97d5-d0db8ea39810" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f0b43901-b45c-478a-b1f8-0b57e4452806" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_ecc311e9-0f0e-4613-b7fa-a006b905636e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f0b43901-b45c-478a-b1f8-0b57e4452806" xlink:to="loc_us-gaap_RestrictedStockMember_ecc311e9-0f0e-4613-b7fa-a006b905636e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_75345be2-d904-4029-8620-9e0f3f439763" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f0b43901-b45c-478a-b1f8-0b57e4452806" xlink:to="loc_us-gaap_EmployeeStockOptionMember_75345be2-d904-4029-8620-9e0f3f439763" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_6a6858f7-d703-4921-be5c-12066ddfc123" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f0b43901-b45c-478a-b1f8-0b57e4452806" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_6a6858f7-d703-4921-be5c-12066ddfc123" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_33e2f38b-1ac2-44b2-88fc-429348823ab0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27816b6d-c8b3-4ba6-87cc-c9f275f6ac0c" xlink:to="loc_us-gaap_StatementClassOfStockAxis_33e2f38b-1ac2-44b2-88fc-429348823ab0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_33e2f38b-1ac2-44b2-88fc-429348823ab0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_33e2f38b-1ac2-44b2-88fc-429348823ab0" xlink:to="loc_us-gaap_ClassOfStockDomain_33e2f38b-1ac2-44b2-88fc-429348823ab0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_1c460641-99ac-4368-add4-d754a0b57427" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_33e2f38b-1ac2-44b2-88fc-429348823ab0" xlink:to="loc_us-gaap_ClassOfStockDomain_1c460641-99ac-4368-add4-d754a0b57427" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PreIPOB1Member_feb5dc1a-f479-4ae8-8e82-5bbead11bde6" xlink:href="shc-20241231.xsd#shc_PreIPOB1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_1c460641-99ac-4368-add4-d754a0b57427" xlink:to="loc_shc_PreIPOB1Member_feb5dc1a-f479-4ae8-8e82-5bbead11bde6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PreIPOB2Member_3f637cb1-a4d3-4cea-a8b3-265719513582" xlink:href="shc-20241231.xsd#shc_PreIPOB2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_1c460641-99ac-4368-add4-d754a0b57427" xlink:to="loc_shc_PreIPOB2Member_3f637cb1-a4d3-4cea-a8b3-265719513582" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_4916a1dc-4674-4c32-b051-1bf63bff0a39" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27816b6d-c8b3-4ba6-87cc-c9f275f6ac0c" xlink:to="loc_us-gaap_PlanNameAxis_4916a1dc-4674-4c32-b051-1bf63bff0a39" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_4916a1dc-4674-4c32-b051-1bf63bff0a39_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_4916a1dc-4674-4c32-b051-1bf63bff0a39" xlink:to="loc_us-gaap_PlanNameDomain_4916a1dc-4674-4c32-b051-1bf63bff0a39_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_52963aa6-a86c-4f89-9819-bc8190a60215" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_4916a1dc-4674-4c32-b051-1bf63bff0a39" xlink:to="loc_us-gaap_PlanNameDomain_52963aa6-a86c-4f89-9819-bc8190a60215" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_A2020OmnibusIncentivePlanMember_0dfea153-d515-4470-a408-03c20fb98a12" xlink:href="shc-20241231.xsd#shc_A2020OmnibusIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_52963aa6-a86c-4f89-9819-bc8190a60215" xlink:to="loc_shc_A2020OmnibusIncentivePlanMember_0dfea153-d515-4470-a408-03c20fb98a12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_6f21aff6-5396-42e9-a41a-3edd2589aae5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27816b6d-c8b3-4ba6-87cc-c9f275f6ac0c" xlink:to="loc_us-gaap_VestingAxis_6f21aff6-5396-42e9-a41a-3edd2589aae5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_6f21aff6-5396-42e9-a41a-3edd2589aae5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_6f21aff6-5396-42e9-a41a-3edd2589aae5" xlink:to="loc_us-gaap_VestingDomain_6f21aff6-5396-42e9-a41a-3edd2589aae5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_c9ef3b52-5030-4e05-9ecf-f8c8a80c67b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_6f21aff6-5396-42e9-a41a-3edd2589aae5" xlink:to="loc_us-gaap_VestingDomain_c9ef3b52-5030-4e05-9ecf-f8c8a80c67b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_edca4d51-ff35-424d-b72d-010ec263c699" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_c9ef3b52-5030-4e05-9ecf-f8c8a80c67b3" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_edca4d51-ff35-424d-b72d-010ec263c699" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_dda2cb94-58f0-439c-a5c5-8918064b9446" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_c9ef3b52-5030-4e05-9ecf-f8c8a80c67b3" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_dda2cb94-58f0-439c-a5c5-8918064b9446" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_5a1a609c-f148-463a-81a2-098bcae62ed1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationAwardTrancheThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_c9ef3b52-5030-4e05-9ecf-f8c8a80c67b3" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_5a1a609c-f148-463a-81a2-098bcae62ed1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_ShareBasedPaymentArrangementTrancheFourMember_280cf318-4345-4789-97c5-ba687be582bf" xlink:href="shc-20241231.xsd#shc_ShareBasedPaymentArrangementTrancheFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_c9ef3b52-5030-4e05-9ecf-f8c8a80c67b3" xlink:to="loc_shc_ShareBasedPaymentArrangementTrancheFourMember_280cf318-4345-4789-97c5-ba687be582bf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_ShareBasedPaymentArrangementTrancheFiveMember_e5e26a0c-0169-446f-afce-625889ea334e" xlink:href="shc-20241231.xsd#shc_ShareBasedPaymentArrangementTrancheFiveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_c9ef3b52-5030-4e05-9ecf-f8c8a80c67b3" xlink:to="loc_shc_ShareBasedPaymentArrangementTrancheFiveMember_e5e26a0c-0169-446f-afce-625889ea334e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_1f1e6e96-a100-4425-9a17-b1f5c9573058" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27816b6d-c8b3-4ba6-87cc-c9f275f6ac0c" xlink:to="loc_srt_RangeAxis_1f1e6e96-a100-4425-9a17-b1f5c9573058" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_1f1e6e96-a100-4425-9a17-b1f5c9573058_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_1f1e6e96-a100-4425-9a17-b1f5c9573058" xlink:to="loc_srt_RangeMember_1f1e6e96-a100-4425-9a17-b1f5c9573058_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ba2bea7e-c504-4067-9c55-01d0c3062520" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_1f1e6e96-a100-4425-9a17-b1f5c9573058" xlink:to="loc_srt_RangeMember_ba2bea7e-c504-4067-9c55-01d0c3062520" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_f8c3e450-dc05-499c-b7dd-8e85ca2b7a0f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ba2bea7e-c504-4067-9c55-01d0c3062520" xlink:to="loc_srt_MinimumMember_f8c3e450-dc05-499c-b7dd-8e85ca2b7a0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_716070e2-b406-43ec-990c-60eae61c5cb3" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ba2bea7e-c504-4067-9c55-01d0c3062520" xlink:to="loc_srt_MaximumMember_716070e2-b406-43ec-990c-60eae61c5cb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_25635c74-149e-4562-8224-c2a55b34cc5e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_25635c74-149e-4562-8224-c2a55b34cc5e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_15fc8713-53a4-4b55-ae8d-aef00a7e2cca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_15fc8713-53a4-4b55-ae8d-aef00a7e2cca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_CashProceedsToSponsorsRatioToInvestedCapital_3edd186b-d677-430b-a517-ef123fc04c67" xlink:href="shc-20241231.xsd#shc_CashProceedsToSponsorsRatioToInvestedCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_shc_CashProceedsToSponsorsRatioToInvestedCapital_3edd186b-d677-430b-a517-ef123fc04c67" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_InvestmentInternalRateOfReturn_247ef420-c4d4-4981-ae5a-ed9b650d3db0" xlink:href="shc-20241231.xsd#shc_InvestmentInternalRateOfReturn"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_shc_InvestmentInternalRateOfReturn_247ef420-c4d4-4981-ae5a-ed9b650d3db0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_6f6c2c9e-7db4-43e2-b299-7eab2f016f33" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_6f6c2c9e-7db4-43e2-b299-7eab2f016f33" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_bd016e65-5aa9-4304-91a5-63595876bfaf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_bd016e65-5aa9-4304-91a5-63595876bfaf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_edcf6425-c93d-4d1e-af1c-6e506fd49d1e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_edcf6425-c93d-4d1e-af1c-6e506fd49d1e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_a3a352a9-1b20-454c-a892-fe67b4caeb36" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_a3a352a9-1b20-454c-a892-fe67b4caeb36" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_70a3d490-9c26-4f87-9f4a-3744c934974e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_70a3d490-9c26-4f87-9f4a-3744c934974e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_574cac8e-d2b9-42a7-aa8b-6161e9c6f275" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_574cac8e-d2b9-42a7-aa8b-6161e9c6f275" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_5bbd47e9-0fe3-495c-8f42-78dc73c26157" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1a22f877-e856-4fed-887a-2e6a5d52a8ee" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_5bbd47e9-0fe3-495c-8f42-78dc73c26157" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/ShareBasedCompensationScheduleofNonvestedRestrictedStockUnitsActivityDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#ShareBasedCompensationScheduleofNonvestedRestrictedStockUnitsActivityDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/ShareBasedCompensationScheduleofNonvestedRestrictedStockUnitsActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f16e803f-99a5-4414-919d-a70eeeee3a47" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e8e77b42-5a58-4211-8467-142171e72ebd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f16e803f-99a5-4414-919d-a70eeeee3a47" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e8e77b42-5a58-4211-8467-142171e72ebd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_2657b2dd-983f-4145-a506-3af969773cde" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e8e77b42-5a58-4211-8467-142171e72ebd" xlink:to="loc_us-gaap_AwardTypeAxis_2657b2dd-983f-4145-a506-3af969773cde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2657b2dd-983f-4145-a506-3af969773cde_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_2657b2dd-983f-4145-a506-3af969773cde" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2657b2dd-983f-4145-a506-3af969773cde_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1d15b374-3d20-4f2e-b875-fae57e478cb3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_2657b2dd-983f-4145-a506-3af969773cde" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1d15b374-3d20-4f2e-b875-fae57e478cb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_f1a2ef17-4b5a-46ea-9e64-4fc18bcddff0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1d15b374-3d20-4f2e-b875-fae57e478cb3" xlink:to="loc_us-gaap_RestrictedStockMember_f1a2ef17-4b5a-46ea-9e64-4fc18bcddff0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_10610516-bd0b-4116-9ac3-7bd1f364946d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e8e77b42-5a58-4211-8467-142171e72ebd" xlink:to="loc_us-gaap_StatementClassOfStockAxis_10610516-bd0b-4116-9ac3-7bd1f364946d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_10610516-bd0b-4116-9ac3-7bd1f364946d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_10610516-bd0b-4116-9ac3-7bd1f364946d" xlink:to="loc_us-gaap_ClassOfStockDomain_10610516-bd0b-4116-9ac3-7bd1f364946d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_43732df2-7494-4d4d-9a32-73dd5705e139" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_10610516-bd0b-4116-9ac3-7bd1f364946d" xlink:to="loc_us-gaap_ClassOfStockDomain_43732df2-7494-4d4d-9a32-73dd5705e139" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PreIPOB1Member_f08e86cb-01fd-4013-956d-32780e64ab36" xlink:href="shc-20241231.xsd#shc_PreIPOB1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_43732df2-7494-4d4d-9a32-73dd5705e139" xlink:to="loc_shc_PreIPOB1Member_f08e86cb-01fd-4013-956d-32780e64ab36" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PreIPOB2Member_7e9d27b1-69fe-4d07-8226-de373327becf" xlink:href="shc-20241231.xsd#shc_PreIPOB2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_43732df2-7494-4d4d-9a32-73dd5705e139" xlink:to="loc_shc_PreIPOB2Member_7e9d27b1-69fe-4d07-8226-de373327becf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dc2fd0d1-7416-47e4-853f-bc2bad1b492e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f16e803f-99a5-4414-919d-a70eeeee3a47" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dc2fd0d1-7416-47e4-853f-bc2bad1b492e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6f4dacb5-6dc2-43b9-b16d-f7118ed7d49b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dc2fd0d1-7416-47e4-853f-bc2bad1b492e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6f4dacb5-6dc2-43b9-b16d-f7118ed7d49b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_02950fa4-a1c6-41e2-8299-49ec2142b976" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dc2fd0d1-7416-47e4-853f-bc2bad1b492e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_02950fa4-a1c6-41e2-8299-49ec2142b976" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_0df97fb5-2fcf-4ff5-82f7-2fe938e4aee8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dc2fd0d1-7416-47e4-853f-bc2bad1b492e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_0df97fb5-2fcf-4ff5-82f7-2fe938e4aee8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_fa53b2d0-9c5f-4d9b-b8b5-9f775ac5b101" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/ShareBasedCompensationScheduleofCompensationCostandUnrecognizedCompensationcostforthePreIPOAwardsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#ShareBasedCompensationScheduleofCompensationCostandUnrecognizedCompensationcostforthePreIPOAwardsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/ShareBasedCompensationScheduleofCompensationCostandUnrecognizedCompensationcostforthePreIPOAwardsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c3ab18e5-add2-4913-bcec-d8790cea0022" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_fb947a02-05c1-4f0e-8992-52cb80fd87df" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c3ab18e5-add2-4913-bcec-d8790cea0022" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_fb947a02-05c1-4f0e-8992-52cb80fd87df" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_64da5304-d3cf-4617-ac54-b80d08a440f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_fb947a02-05c1-4f0e-8992-52cb80fd87df" xlink:to="loc_us-gaap_AwardTypeAxis_64da5304-d3cf-4617-ac54-b80d08a440f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_64da5304-d3cf-4617-ac54-b80d08a440f0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_64da5304-d3cf-4617-ac54-b80d08a440f0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_64da5304-d3cf-4617-ac54-b80d08a440f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a3acf0d5-571a-40e1-8707-a76519680321" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_64da5304-d3cf-4617-ac54-b80d08a440f0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a3acf0d5-571a-40e1-8707-a76519680321" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_213bdd3a-faea-4c0e-abf6-80f76d9b8f59" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a3acf0d5-571a-40e1-8707-a76519680321" xlink:to="loc_us-gaap_RestrictedStockMember_213bdd3a-faea-4c0e-abf6-80f76d9b8f59" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_2344cbdf-c390-4451-8b0a-e4ab144928b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_fb947a02-05c1-4f0e-8992-52cb80fd87df" xlink:to="loc_us-gaap_StatementClassOfStockAxis_2344cbdf-c390-4451-8b0a-e4ab144928b3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_2344cbdf-c390-4451-8b0a-e4ab144928b3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2344cbdf-c390-4451-8b0a-e4ab144928b3" xlink:to="loc_us-gaap_ClassOfStockDomain_2344cbdf-c390-4451-8b0a-e4ab144928b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_5d74d4a9-e262-4c1b-9d74-fe9e976f6c1f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2344cbdf-c390-4451-8b0a-e4ab144928b3" xlink:to="loc_us-gaap_ClassOfStockDomain_5d74d4a9-e262-4c1b-9d74-fe9e976f6c1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PreIPOB1Member_370585b6-1c97-47d8-8de7-96eb0f2d1f05" xlink:href="shc-20241231.xsd#shc_PreIPOB1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5d74d4a9-e262-4c1b-9d74-fe9e976f6c1f" xlink:to="loc_shc_PreIPOB1Member_370585b6-1c97-47d8-8de7-96eb0f2d1f05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PreIPOB2Member_595d0279-bf12-4e24-8be4-b4723e5b8925" xlink:href="shc-20241231.xsd#shc_PreIPOB2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5d74d4a9-e262-4c1b-9d74-fe9e976f6c1f" xlink:to="loc_shc_PreIPOB2Member_595d0279-bf12-4e24-8be4-b4723e5b8925" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_8268061d-4a9f-4b4b-a07a-e7f31624b36d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c3ab18e5-add2-4913-bcec-d8790cea0022" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_8268061d-4a9f-4b4b-a07a-e7f31624b36d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_d4759834-0299-4af1-a3e8-6e3a1a4e7ea2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c3ab18e5-add2-4913-bcec-d8790cea0022" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_d4759834-0299-4af1-a3e8-6e3a1a4e7ea2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_d027faca-0e2b-4f39-b739-406cc83425a5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c3ab18e5-add2-4913-bcec-d8790cea0022" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_d027faca-0e2b-4f39-b739-406cc83425a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_0b279fd7-2055-4f74-ae03-46f1a3e840ae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c3ab18e5-add2-4913-bcec-d8790cea0022" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_0b279fd7-2055-4f74-ae03-46f1a3e840ae" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/ShareBasedCompensationScheduleofStockOptionsAssumptionsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#ShareBasedCompensationScheduleofStockOptionsAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/ShareBasedCompensationScheduleofStockOptionsAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5e16fce9-895b-40ee-9663-85b123afdb04" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_83d632d8-a5c9-4384-b455-67487aed1c60" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5e16fce9-895b-40ee-9663-85b123afdb04" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_83d632d8-a5c9-4384-b455-67487aed1c60" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_f2b2e71d-3efb-48be-b2bb-88da2294c0e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_83d632d8-a5c9-4384-b455-67487aed1c60" xlink:to="loc_us-gaap_AwardTypeAxis_f2b2e71d-3efb-48be-b2bb-88da2294c0e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f2b2e71d-3efb-48be-b2bb-88da2294c0e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_f2b2e71d-3efb-48be-b2bb-88da2294c0e9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f2b2e71d-3efb-48be-b2bb-88da2294c0e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3b2d9e4b-9c9d-43d0-87ae-13ef89f7223a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_f2b2e71d-3efb-48be-b2bb-88da2294c0e9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3b2d9e4b-9c9d-43d0-87ae-13ef89f7223a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_1107a345-0133-47fb-9ff6-9a0164617a5e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3b2d9e4b-9c9d-43d0-87ae-13ef89f7223a" xlink:to="loc_us-gaap_EmployeeStockOptionMember_1107a345-0133-47fb-9ff6-9a0164617a5e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_a8c2593d-07e1-44f6-8db5-0293202fb741" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5e16fce9-895b-40ee-9663-85b123afdb04" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_a8c2593d-07e1-44f6-8db5-0293202fb741" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_26b1450b-4949-4373-9f87-49c6c6b2bc73" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5e16fce9-895b-40ee-9663-85b123afdb04" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_26b1450b-4949-4373-9f87-49c6c6b2bc73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_6e24ed6c-0dea-43d8-b7b9-699dd075f0dd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5e16fce9-895b-40ee-9663-85b123afdb04" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_6e24ed6c-0dea-43d8-b7b9-699dd075f0dd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_93caf0b9-6404-4788-9f9d-aa514b0f79fc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5e16fce9-895b-40ee-9663-85b123afdb04" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_93caf0b9-6404-4788-9f9d-aa514b0f79fc" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/ShareBasedCompensationScheduleofUnvestedRSUsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#ShareBasedCompensationScheduleofUnvestedRSUsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/ShareBasedCompensationScheduleofUnvestedRSUsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4ae8b024-6e98-4fdb-b8e5-5bda055f69e6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6d44def7-17e1-434d-a6ed-44c7fb8609b6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4ae8b024-6e98-4fdb-b8e5-5bda055f69e6" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6d44def7-17e1-434d-a6ed-44c7fb8609b6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_b609274f-d092-4f50-bf4b-b93b9981aa46" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6d44def7-17e1-434d-a6ed-44c7fb8609b6" xlink:to="loc_us-gaap_AwardTypeAxis_b609274f-d092-4f50-bf4b-b93b9981aa46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b609274f-d092-4f50-bf4b-b93b9981aa46_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_b609274f-d092-4f50-bf4b-b93b9981aa46" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b609274f-d092-4f50-bf4b-b93b9981aa46_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dfb9f325-ab6f-45e2-9457-a15fe360a9d8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_b609274f-d092-4f50-bf4b-b93b9981aa46" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dfb9f325-ab6f-45e2-9457-a15fe360a9d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_9be7fc81-393e-4330-ad04-df6bc45457fc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dfb9f325-ab6f-45e2-9457-a15fe360a9d8" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_9be7fc81-393e-4330-ad04-df6bc45457fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7e9be608-408b-4999-954e-55aff4ab6087" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4ae8b024-6e98-4fdb-b8e5-5bda055f69e6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7e9be608-408b-4999-954e-55aff4ab6087" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_f8797d9a-a29d-4243-b65f-ae9e011d7370" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7e9be608-408b-4999-954e-55aff4ab6087" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_f8797d9a-a29d-4243-b65f-ae9e011d7370" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_43de886f-ac89-4c27-befb-d46fe287ef94" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7e9be608-408b-4999-954e-55aff4ab6087" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_43de886f-ac89-4c27-befb-d46fe287ef94" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_3e4ec550-616a-4898-99d9-601726c58fd3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7e9be608-408b-4999-954e-55aff4ab6087" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_3e4ec550-616a-4898-99d9-601726c58fd3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_ee2e9e96-6b0b-4a1f-b3b7-a095cd043dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7e9be608-408b-4999-954e-55aff4ab6087" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_ee2e9e96-6b0b-4a1f-b3b7-a095cd043dcb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_5abdee61-830d-44c2-af3d-ba9490fe2efd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_20514520-ed0b-4b94-8748-1d7f30307964" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4ae8b024-6e98-4fdb-b8e5-5bda055f69e6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_20514520-ed0b-4b94-8748-1d7f30307964" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_cffca85e-6952-4bc6-a32f-eca5e6372007" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_20514520-ed0b-4b94-8748-1d7f30307964" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_cffca85e-6952-4bc6-a32f-eca5e6372007" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_53db05a1-4037-44ae-8ef2-a58e18a9b3e2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_20514520-ed0b-4b94-8748-1d7f30307964" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_53db05a1-4037-44ae-8ef2-a58e18a9b3e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_af4176e6-8881-4c04-bdc8-7b5ad67b77c0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_20514520-ed0b-4b94-8748-1d7f30307964" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_af4176e6-8881-4c04-bdc8-7b5ad67b77c0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_f81c4715-ba1d-4811-bc35-75c44e73673b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_20514520-ed0b-4b94-8748-1d7f30307964" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_f81c4715-ba1d-4811-bc35-75c44e73673b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ab209b3a-a359-4535-ada5-0ceafe3e1cae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/EarningsLossPerShareDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#EarningsLossPerShareDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/EarningsLossPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_b6c49b2c-0eb1-40f7-95f4-a8544d43af79" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_a66133d8-cf46-43a8-9c5c-e7ca538de381" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_b6c49b2c-0eb1-40f7-95f4-a8544d43af79" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_a66133d8-cf46-43a8-9c5c-e7ca538de381" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_3c449b77-7046-4dc1-99ac-4647e07fae09" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_a66133d8-cf46-43a8-9c5c-e7ca538de381" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_3c449b77-7046-4dc1-99ac-4647e07fae09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3c449b77-7046-4dc1-99ac-4647e07fae09_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_3c449b77-7046-4dc1-99ac-4647e07fae09" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3c449b77-7046-4dc1-99ac-4647e07fae09_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e3b01335-cc3c-42cc-a588-2f48b07208df" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_3c449b77-7046-4dc1-99ac-4647e07fae09" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e3b01335-cc3c-42cc-a588-2f48b07208df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_bb5dc1ed-f31b-4f81-b588-99dee7c75c5d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e3b01335-cc3c-42cc-a588-2f48b07208df" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_bb5dc1ed-f31b-4f81-b588-99dee7c75c5d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_6569b9aa-38ec-4942-8433-37adfaa0a44b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e3b01335-cc3c-42cc-a588-2f48b07208df" xlink:to="loc_us-gaap_EmployeeStockOptionMember_6569b9aa-38ec-4942-8433-37adfaa0a44b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_d907fa5c-9747-4ee5-a358-98a99e88712c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_b6c49b2c-0eb1-40f7-95f4-a8544d43af79" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_d907fa5c-9747-4ee5-a358-98a99e88712c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainContingenciesLineItems_f9bd31b5-0cb9-4d6e-96fe-d97dc40af8a2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainContingenciesTable_1a6f5df1-e4fc-47da-b1e2-4113a2508c7c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GainContingenciesLineItems_f9bd31b5-0cb9-4d6e-96fe-d97dc40af8a2" xlink:to="loc_us-gaap_GainContingenciesTable_1a6f5df1-e4fc-47da-b1e2-4113a2508c7c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_357881cf-b4db-4d41-b9aa-3f29e461f250" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_GainContingenciesTable_1a6f5df1-e4fc-47da-b1e2-4113a2508c7c" xlink:to="loc_srt_LitigationCaseAxis_357881cf-b4db-4d41-b9aa-3f29e461f250" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_357881cf-b4db-4d41-b9aa-3f29e461f250_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_357881cf-b4db-4d41-b9aa-3f29e461f250" xlink:to="loc_srt_LitigationCaseTypeDomain_357881cf-b4db-4d41-b9aa-3f29e461f250_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_1def11e4-07d9-4ae7-8fca-1d2194596d71" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_357881cf-b4db-4d41-b9aa-3f29e461f250" xlink:to="loc_srt_LitigationCaseTypeDomain_1def11e4-07d9-4ae7-8fca-1d2194596d71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_AssetTransferCaseMember_e5822e5a-19ae-4209-b845-3feca2326409" xlink:href="shc-20241231.xsd#shc_AssetTransferCaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_1def11e4-07d9-4ae7-8fca-1d2194596d71" xlink:to="loc_shc_AssetTransferCaseMember_e5822e5a-19ae-4209-b845-3feca2326409" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationGeorgiaMember_04239423-b97c-4b75-9ccd-972e8845a180" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationGeorgiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_1def11e4-07d9-4ae7-8fca-1d2194596d71" xlink:to="loc_shc_EthyleneOxideTortLitigationGeorgiaMember_04239423-b97c-4b75-9ccd-972e8845a180" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationIllinoisMember_3a4391a5-d99e-45fc-a74e-2487b9cddf91" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationIllinoisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_1def11e4-07d9-4ae7-8fca-1d2194596d71" xlink:to="loc_shc_EthyleneOxideTortLitigationIllinoisMember_3a4391a5-d99e-45fc-a74e-2487b9cddf91" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_e222eb66-2636-4156-88be-8b2038e3f977" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_GainContingenciesTable_1a6f5df1-e4fc-47da-b1e2-4113a2508c7c" xlink:to="loc_us-gaap_LitigationStatusAxis_e222eb66-2636-4156-88be-8b2038e3f977" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_e222eb66-2636-4156-88be-8b2038e3f977_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_e222eb66-2636-4156-88be-8b2038e3f977" xlink:to="loc_us-gaap_LitigationStatusDomain_e222eb66-2636-4156-88be-8b2038e3f977_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_f9c3c80b-5ac3-45bb-a762-2a1fffac0ed1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_e222eb66-2636-4156-88be-8b2038e3f977" xlink:to="loc_us-gaap_LitigationStatusDomain_f9c3c80b-5ac3-45bb-a762-2a1fffac0ed1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_63403513-5d4d-4e7b-becc-977d2a0137ae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_f9c3c80b-5ac3-45bb-a762-2a1fffac0ed1" xlink:to="loc_us-gaap_PendingLitigationMember_63403513-5d4d-4e7b-becc-977d2a0137ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TriggeringEventAxis_528203a3-0742-4987-8277-b765a5cb1323" xlink:href="shc-20241231.xsd#shc_TriggeringEventAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_GainContingenciesTable_1a6f5df1-e4fc-47da-b1e2-4113a2508c7c" xlink:to="loc_shc_TriggeringEventAxis_528203a3-0742-4987-8277-b765a5cb1323" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TriggeringEventDomain_528203a3-0742-4987-8277-b765a5cb1323_default" xlink:href="shc-20241231.xsd#shc_TriggeringEventDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_shc_TriggeringEventAxis_528203a3-0742-4987-8277-b765a5cb1323" xlink:to="loc_shc_TriggeringEventDomain_528203a3-0742-4987-8277-b765a5cb1323_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TriggeringEventDomain_c05ef37f-f9d4-4ea1-ab73-9fcef291ef39" xlink:href="shc-20241231.xsd#shc_TriggeringEventDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_shc_TriggeringEventAxis_528203a3-0742-4987-8277-b765a5cb1323" xlink:to="loc_shc_TriggeringEventDomain_c05ef37f-f9d4-4ea1-ab73-9fcef291ef39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_ConsolidatedForPretrialPurposesMember_29eee1bd-3135-4272-ae88-690312cf95d7" xlink:href="shc-20241231.xsd#shc_ConsolidatedForPretrialPurposesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_TriggeringEventDomain_c05ef37f-f9d4-4ea1-ab73-9fcef291ef39" xlink:to="loc_shc_ConsolidatedForPretrialPurposesMember_29eee1bd-3135-4272-ae88-690312cf95d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SetForTrialInApril2025Member_eae4c74b-8948-4339-b34a-7b0f24f15083" xlink:href="shc-20241231.xsd#shc_SetForTrialInApril2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_TriggeringEventDomain_c05ef37f-f9d4-4ea1-ab73-9fcef291ef39" xlink:to="loc_shc_SetForTrialInApril2025Member_eae4c74b-8948-4339-b34a-7b0f24f15083" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SetForTrialInJune2025Member_0ea7a7fd-9281-443c-93a4-da3aba7b3a03" xlink:href="shc-20241231.xsd#shc_SetForTrialInJune2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_TriggeringEventDomain_c05ef37f-f9d4-4ea1-ab73-9fcef291ef39" xlink:to="loc_shc_SetForTrialInJune2025Member_0ea7a7fd-9281-443c-93a4-da3aba7b3a03" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_e7ad391b-f6fd-4893-86e3-05fa869efb2c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_GainContingenciesTable_1a6f5df1-e4fc-47da-b1e2-4113a2508c7c" xlink:to="loc_srt_StatementGeographicalAxis_e7ad391b-f6fd-4893-86e3-05fa869efb2c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_e7ad391b-f6fd-4893-86e3-05fa869efb2c_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_e7ad391b-f6fd-4893-86e3-05fa869efb2c" xlink:to="loc_srt_SegmentGeographicalDomain_e7ad391b-f6fd-4893-86e3-05fa869efb2c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_2ee8de58-350d-494b-9857-3b9b58ebaab1" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_e7ad391b-f6fd-4893-86e3-05fa869efb2c" xlink:to="loc_srt_SegmentGeographicalDomain_2ee8de58-350d-494b-9857-3b9b58ebaab1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_CA_6ac46c1e-7cee-4013-ab59-4802d7d88429" xlink:href="https://xbrl.sec.gov/stpr/2024/stpr-2024.xsd#stpr_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_2ee8de58-350d-494b-9857-3b9b58ebaab1" xlink:to="loc_stpr_CA_6ac46c1e-7cee-4013-ab59-4802d7d88429" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_GA_935e4305-c107-462b-bdd4-31af770a841b" xlink:href="https://xbrl.sec.gov/stpr/2024/stpr-2024.xsd#stpr_GA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_2ee8de58-350d-494b-9857-3b9b58ebaab1" xlink:to="loc_stpr_GA_935e4305-c107-462b-bdd4-31af770a841b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_IL_14ccff76-705f-42f4-b99d-0fe7df95d572" xlink:href="https://xbrl.sec.gov/stpr/2024/stpr-2024.xsd#stpr_IL"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_2ee8de58-350d-494b-9857-3b9b58ebaab1" xlink:to="loc_stpr_IL_14ccff76-705f-42f4-b99d-0fe7df95d572" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_c0a5a591-0f0c-445a-af4d-71015374f840" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_GainContingenciesTable_1a6f5df1-e4fc-47da-b1e2-4113a2508c7c" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_c0a5a591-0f0c-445a-af4d-71015374f840" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_c0a5a591-0f0c-445a-af4d-71015374f840_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_c0a5a591-0f0c-445a-af4d-71015374f840" xlink:to="loc_us-gaap_LossContingencyNatureDomain_c0a5a591-0f0c-445a-af4d-71015374f840_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_79d83d26-5c1d-46c4-80eb-1f6d2ee215b7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_c0a5a591-0f0c-445a-af4d-71015374f840" xlink:to="loc_us-gaap_LossContingencyNatureDomain_79d83d26-5c1d-46c4-80eb-1f6d2ee215b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PersonalInjuryAndWrongfulDeathMember_7cb442c7-0307-43e2-8ff4-24484c7fda5c" xlink:href="shc-20241231.xsd#shc_PersonalInjuryAndWrongfulDeathMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_79d83d26-5c1d-46c4-80eb-1f6d2ee215b7" xlink:to="loc_shc_PersonalInjuryAndWrongfulDeathMember_7cb442c7-0307-43e2-8ff4-24484c7fda5c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PersonalInjuryMember_2f883867-b793-4472-8ee5-35cc895d1f6c" xlink:href="shc-20241231.xsd#shc_PersonalInjuryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_79d83d26-5c1d-46c4-80eb-1f6d2ee215b7" xlink:to="loc_shc_PersonalInjuryMember_2f883867-b793-4472-8ee5-35cc895d1f6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PropertyDevaluationMember_5532e73a-54dc-4b3c-ab5e-e73838d60a4c" xlink:href="shc-20241231.xsd#shc_PropertyDevaluationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_79d83d26-5c1d-46c4-80eb-1f6d2ee215b7" xlink:to="loc_shc_PropertyDevaluationMember_5532e73a-54dc-4b3c-ab5e-e73838d60a4c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_9c86484f-c1dd-4f49-ad41-6017e329ee86" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_GainContingenciesTable_1a6f5df1-e4fc-47da-b1e2-4113a2508c7c" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_9c86484f-c1dd-4f49-ad41-6017e329ee86" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_9c86484f-c1dd-4f49-ad41-6017e329ee86_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_9c86484f-c1dd-4f49-ad41-6017e329ee86" xlink:to="loc_us-gaap_SegmentDomain_9c86484f-c1dd-4f49-ad41-6017e329ee86_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_ab15e833-b897-4aa3-895a-745a2d1c55f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_9c86484f-c1dd-4f49-ad41-6017e329ee86" xlink:to="loc_us-gaap_SegmentDomain_ab15e833-b897-4aa3-895a-745a2d1c55f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NordionMember_22a36d4f-f289-4cce-a5ac-1a8ad8451ff8" xlink:href="shc-20241231.xsd#shc_NordionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_ab15e833-b897-4aa3-895a-745a2d1c55f3" xlink:to="loc_shc_NordionMember_22a36d4f-f289-4cce-a5ac-1a8ad8451ff8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted_21c5d39c-44cf-4b4f-a403-0fc2ab7660fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingenciesLineItems_f9bd31b5-0cb9-4d6e-96fe-d97dc40af8a2" xlink:to="loc_us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted_21c5d39c-44cf-4b4f-a403-0fc2ab7660fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_ec9e6f33-3155-4baf-9a1e-3b4b6772b127" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingenciesLineItems_f9bd31b5-0cb9-4d6e-96fe-d97dc40af8a2" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_ec9e6f33-3155-4baf-9a1e-3b4b6772b127" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NumberOfCasesThatWillProceedToJudicialDetermination_270da9e4-fa40-432a-8ba1-6119b2fe4b49" xlink:href="shc-20241231.xsd#shc_NumberOfCasesThatWillProceedToJudicialDetermination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingenciesLineItems_f9bd31b5-0cb9-4d6e-96fe-d97dc40af8a2" xlink:to="loc_shc_NumberOfCasesThatWillProceedToJudicialDetermination_270da9e4-fa40-432a-8ba1-6119b2fe4b49" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NumberOfCasesIncludingPersonalInjuryAndPropertyClaims_3accdac1-de82-46e7-a087-03234484ca2d" xlink:href="shc-20241231.xsd#shc_NumberOfCasesIncludingPersonalInjuryAndPropertyClaims"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingenciesLineItems_f9bd31b5-0cb9-4d6e-96fe-d97dc40af8a2" xlink:to="loc_shc_NumberOfCasesIncludingPersonalInjuryAndPropertyClaims_3accdac1-de82-46e7-a087-03234484ca2d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNewClaimsFiledNumber_787e56e3-5d19-4395-9700-1cee4b9688fc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyNewClaimsFiledNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingenciesLineItems_f9bd31b5-0cb9-4d6e-96fe-d97dc40af8a2" xlink:to="loc_us-gaap_LossContingencyNewClaimsFiledNumber_787e56e3-5d19-4395-9700-1cee4b9688fc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiabilityPerOccurrence_4ceaaccf-8698-4a10-a15b-c34e41cb6bd9" xlink:href="shc-20241231.xsd#shc_LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiabilityPerOccurrence"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingenciesLineItems_f9bd31b5-0cb9-4d6e-96fe-d97dc40af8a2" xlink:to="loc_shc_LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiabilityPerOccurrence_4ceaaccf-8698-4a10-a15b-c34e41cb6bd9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability_83597927-2702-4088-957c-a1e69a237859" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingenciesLineItems_f9bd31b5-0cb9-4d6e-96fe-d97dc40af8a2" xlink:to="loc_us-gaap_LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability_83597927-2702-4088-957c-a1e69a237859" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_GrossSettlementAndDefenseCostsIncurred_8e62de27-afab-43af-941d-3b9b3eae3d50" xlink:href="shc-20241231.xsd#shc_GrossSettlementAndDefenseCostsIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingenciesLineItems_f9bd31b5-0cb9-4d6e-96fe-d97dc40af8a2" xlink:to="loc_shc_GrossSettlementAndDefenseCostsIncurred_8e62de27-afab-43af-941d-3b9b3eae3d50" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/FinancialInstrumentsandFinancialRiskAdditionalInformationDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#FinancialInstrumentsandFinancialRiskAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/FinancialInstrumentsandFinancialRiskAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_11a9adeb-2586-43f5-8167-648021e6b84d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_10507c82-0441-45c2-b104-9b01406872f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_11a9adeb-2586-43f5-8167-648021e6b84d" xlink:to="loc_us-gaap_DerivativeTable_10507c82-0441-45c2-b104-9b01406872f3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_680284d6-4b61-403b-b6b2-f35f864f57c1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_10507c82-0441-45c2-b104-9b01406872f3" xlink:to="loc_us-gaap_HedgingDesignationAxis_680284d6-4b61-403b-b6b2-f35f864f57c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_680284d6-4b61-403b-b6b2-f35f864f57c1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_680284d6-4b61-403b-b6b2-f35f864f57c1" xlink:to="loc_us-gaap_HedgingDesignationDomain_680284d6-4b61-403b-b6b2-f35f864f57c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_ff5ec4f5-4026-4b27-9812-4a4d1a48d88a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_680284d6-4b61-403b-b6b2-f35f864f57c1" xlink:to="loc_us-gaap_HedgingDesignationDomain_ff5ec4f5-4026-4b27-9812-4a4d1a48d88a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_10ff8ea8-eca3-4daf-908f-8425a279d800" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_ff5ec4f5-4026-4b27-9812-4a4d1a48d88a" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_10ff8ea8-eca3-4daf-908f-8425a279d800" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_e7c41c3e-bb3c-42ec-80cf-1c8856a594b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_10507c82-0441-45c2-b104-9b01406872f3" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_e7c41c3e-bb3c-42ec-80cf-1c8856a594b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_e7c41c3e-bb3c-42ec-80cf-1c8856a594b2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_e7c41c3e-bb3c-42ec-80cf-1c8856a594b2" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_e7c41c3e-bb3c-42ec-80cf-1c8856a594b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_4eed2092-152f-4d65-98fd-0454be8a86ff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_e7c41c3e-bb3c-42ec-80cf-1c8856a594b2" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_4eed2092-152f-4d65-98fd-0454be8a86ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_19d7c5f1-af54-4f77-b781-07ae3aea46ff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_4eed2092-152f-4d65-98fd-0454be8a86ff" xlink:to="loc_us-gaap_InterestRateSwapMember_19d7c5f1-af54-4f77-b781-07ae3aea46ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCapMember_0f95e050-07bd-4efd-8ffc-1f0823cc475a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateCapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_4eed2092-152f-4d65-98fd-0454be8a86ff" xlink:to="loc_us-gaap_InterestRateCapMember_0f95e050-07bd-4efd-8ffc-1f0823cc475a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TriggeringEventAxis_d2af1d2f-f824-49c0-a406-bd76e857b46b" xlink:href="shc-20241231.xsd#shc_TriggeringEventAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_10507c82-0441-45c2-b104-9b01406872f3" xlink:to="loc_shc_TriggeringEventAxis_d2af1d2f-f824-49c0-a406-bd76e857b46b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TriggeringEventDomain_d2af1d2f-f824-49c0-a406-bd76e857b46b_default" xlink:href="shc-20241231.xsd#shc_TriggeringEventDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_shc_TriggeringEventAxis_d2af1d2f-f824-49c0-a406-bd76e857b46b" xlink:to="loc_shc_TriggeringEventDomain_d2af1d2f-f824-49c0-a406-bd76e857b46b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TriggeringEventDomain_b4ef2d9c-c1c5-4d28-91be-b53dcdd6513d" xlink:href="shc-20241231.xsd#shc_TriggeringEventDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_shc_TriggeringEventAxis_d2af1d2f-f824-49c0-a406-bd76e857b46b" xlink:to="loc_shc_TriggeringEventDomain_b4ef2d9c-c1c5-4d28-91be-b53dcdd6513d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_ForwardStartDateBeginningOnJuly312023Member_9c1a1f87-873a-46ac-a3ec-396550d50d3d" xlink:href="shc-20241231.xsd#shc_ForwardStartDateBeginningOnJuly312023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_shc_TriggeringEventDomain_b4ef2d9c-c1c5-4d28-91be-b53dcdd6513d" xlink:to="loc_shc_ForwardStartDateBeginningOnJuly312023Member_9c1a1f87-873a-46ac-a3ec-396550d50d3d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_03a14075-f6ca-40a9-bfa5-9807d4a35157" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_10507c82-0441-45c2-b104-9b01406872f3" xlink:to="loc_us-gaap_VariableRateAxis_03a14075-f6ca-40a9-bfa5-9807d4a35157" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_03a14075-f6ca-40a9-bfa5-9807d4a35157_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_03a14075-f6ca-40a9-bfa5-9807d4a35157" xlink:to="loc_us-gaap_VariableRateDomain_03a14075-f6ca-40a9-bfa5-9807d4a35157_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_60471eb9-d45d-429e-874d-91e2dc8696fb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_03a14075-f6ca-40a9-bfa5-9807d4a35157" xlink:to="loc_us-gaap_VariableRateDomain_60471eb9-d45d-429e-874d-91e2dc8696fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_884718d2-abb7-47bc-806f-649193efc725" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_60471eb9-d45d-429e-874d-91e2dc8696fb" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_884718d2-abb7-47bc-806f-649193efc725" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LondonInterbankOfferedRateLIBORMemberMember_0e655bd7-6706-4767-90b8-e8759bff3d0c" xlink:href="shc-20241231.xsd#shc_LondonInterbankOfferedRateLIBORMemberMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_60471eb9-d45d-429e-874d-91e2dc8696fb" xlink:to="loc_shc_LondonInterbankOfferedRateLIBORMemberMember_0e655bd7-6706-4767-90b8-e8759bff3d0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_e2b8be7f-16d0-4a7b-8dbc-d4eeaaddd08d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_11a9adeb-2586-43f5-8167-648021e6b84d" xlink:to="loc_us-gaap_DerivativeNotionalAmount_e2b8be7f-16d0-4a7b-8dbc-d4eeaaddd08d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_34adcb17-80e3-4691-a91b-4cddd1747601" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_11a9adeb-2586-43f5-8167-648021e6b84d" xlink:to="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_34adcb17-80e3-4691-a91b-4cddd1747601" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DerivativeOptionPremium_e5d0f641-a440-4101-9d81-d96b038b3bc6" xlink:href="shc-20241231.xsd#shc_DerivativeOptionPremium"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_11a9adeb-2586-43f5-8167-648021e6b84d" xlink:to="loc_shc_DerivativeOptionPremium_e5d0f641-a440-4101-9d81-d96b038b3bc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PercentOfBorrowingLimitationDueToCashFlowExposure_d02b27d1-58cb-464f-9d3f-3b354ad16250" xlink:href="shc-20241231.xsd#shc_PercentOfBorrowingLimitationDueToCashFlowExposure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_11a9adeb-2586-43f5-8167-648021e6b84d" xlink:to="loc_shc_PercentOfBorrowingLimitationDueToCashFlowExposure_d02b27d1-58cb-464f-9d3f-3b354ad16250" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax_1efd4f87-ecdb-40c5-b167-48a2e4b089f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_11a9adeb-2586-43f5-8167-648021e6b84d" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax_1efd4f87-ecdb-40c5-b167-48a2e4b089f0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_da2daf60-666c-4595-bac7-0a00249442cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_11a9adeb-2586-43f5-8167-648021e6b84d" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_da2daf60-666c-4595-bac7-0a00249442cd" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/FinancialInstrumentsandFinancialRiskScheduleofDerivativeInstrumentsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#FinancialInstrumentsandFinancialRiskScheduleofDerivativeInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/FinancialInstrumentsandFinancialRiskScheduleofDerivativeInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_91d308a5-92d9-43d5-bc65-a84bc6ecc253" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_92d3822a-2387-4461-b811-61d0fcc841a2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_91d308a5-92d9-43d5-bc65-a84bc6ecc253" xlink:to="loc_us-gaap_DerivativeTable_92d3822a-2387-4461-b811-61d0fcc841a2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_c904fd9c-0509-44ea-a274-da56d502182a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_92d3822a-2387-4461-b811-61d0fcc841a2" xlink:to="loc_us-gaap_HedgingDesignationAxis_c904fd9c-0509-44ea-a274-da56d502182a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_c904fd9c-0509-44ea-a274-da56d502182a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_c904fd9c-0509-44ea-a274-da56d502182a" xlink:to="loc_us-gaap_HedgingDesignationDomain_c904fd9c-0509-44ea-a274-da56d502182a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_1a5c70f3-c735-4cc1-8de8-5e0ac16880fd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_c904fd9c-0509-44ea-a274-da56d502182a" xlink:to="loc_us-gaap_HedgingDesignationDomain_1a5c70f3-c735-4cc1-8de8-5e0ac16880fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_8539cdbb-afca-4c4c-86a7-d6b25516b754" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_1a5c70f3-c735-4cc1-8de8-5e0ac16880fd" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_8539cdbb-afca-4c4c-86a7-d6b25516b754" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_6073f7d0-e29a-4827-b1d4-6568e0db293d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_1a5c70f3-c735-4cc1-8de8-5e0ac16880fd" xlink:to="loc_us-gaap_NondesignatedMember_6073f7d0-e29a-4827-b1d4-6568e0db293d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_dccd873b-7fdf-4a37-8234-04a0c40c5a59" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_92d3822a-2387-4461-b811-61d0fcc841a2" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_dccd873b-7fdf-4a37-8234-04a0c40c5a59" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_dccd873b-7fdf-4a37-8234-04a0c40c5a59_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_dccd873b-7fdf-4a37-8234-04a0c40c5a59" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_dccd873b-7fdf-4a37-8234-04a0c40c5a59_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_302ea66f-cf1d-4b78-bced-4d35a83ae634" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_dccd873b-7fdf-4a37-8234-04a0c40c5a59" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_302ea66f-cf1d-4b78-bced-4d35a83ae634" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCapMember_eaf1a2bb-5130-4211-b99e-4e7e0a490f80" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateCapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_302ea66f-cf1d-4b78-bced-4d35a83ae634" xlink:to="loc_us-gaap_InterestRateCapMember_eaf1a2bb-5130-4211-b99e-4e7e0a490f80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_3625176d-4f47-4058-8071-11ffb2164afb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_302ea66f-cf1d-4b78-bced-4d35a83ae634" xlink:to="loc_us-gaap_InterestRateSwapMember_3625176d-4f47-4058-8071-11ffb2164afb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_d7fd5cd5-108a-4ff9-a053-528467e54df5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_302ea66f-cf1d-4b78-bced-4d35a83ae634" xlink:to="loc_us-gaap_ForeignExchangeContractMember_d7fd5cd5-108a-4ff9-a053-528467e54df5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmbeddedDerivativeFinancialInstrumentsMember_946a3573-aa04-470b-a56c-b842a90cff14" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmbeddedDerivativeFinancialInstrumentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_302ea66f-cf1d-4b78-bced-4d35a83ae634" xlink:to="loc_us-gaap_EmbeddedDerivativeFinancialInstrumentsMember_946a3573-aa04-470b-a56c-b842a90cff14" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_13232f58-2fa5-466e-936f-7c3669272031" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_91d308a5-92d9-43d5-bc65-a84bc6ecc253" xlink:to="loc_us-gaap_DerivativeNotionalAmount_13232f58-2fa5-466e-936f-7c3669272031" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_f735b013-3945-4c55-a12a-ce49fdfcd5bd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_91d308a5-92d9-43d5-bc65-a84bc6ecc253" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_f735b013-3945-4c55-a12a-ce49fdfcd5bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_3d767743-78cf-4b34-adbf-bf1d8edcecf4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_91d308a5-92d9-43d5-bc65-a84bc6ecc253" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_3d767743-78cf-4b34-adbf-bf1d8edcecf4" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/FinancialInstrumentsandFinancialRiskScheduleofActivitiesofDerivativeInstrumentsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#FinancialInstrumentsandFinancialRiskScheduleofActivitiesofDerivativeInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/FinancialInstrumentsandFinancialRiskScheduleofActivitiesofDerivativeInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_a7f83fd8-d201-48d5-a28d-2e845eadbc8f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_1951e387-f130-4cf0-9b2a-646c98036dc9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_a7f83fd8-d201-48d5-a28d-2e845eadbc8f" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_1951e387-f130-4cf0-9b2a-646c98036dc9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_65cd7fee-4208-4569-b71c-07ffb6943bec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_1951e387-f130-4cf0-9b2a-646c98036dc9" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_65cd7fee-4208-4569-b71c-07ffb6943bec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_65cd7fee-4208-4569-b71c-07ffb6943bec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_65cd7fee-4208-4569-b71c-07ffb6943bec" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_65cd7fee-4208-4569-b71c-07ffb6943bec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_fa74b140-3506-4139-b161-91d2daa5bd8b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_65cd7fee-4208-4569-b71c-07ffb6943bec" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_fa74b140-3506-4139-b161-91d2daa5bd8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCapMember_9d3fc24e-f55b-4e0b-b946-ec2768baf4e8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateCapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fa74b140-3506-4139-b161-91d2daa5bd8b" xlink:to="loc_us-gaap_InterestRateCapMember_9d3fc24e-f55b-4e0b-b946-ec2768baf4e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmbeddedDerivativeFinancialInstrumentsMember_84d28a3b-44b6-4eab-aa0a-1d41884a81aa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmbeddedDerivativeFinancialInstrumentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fa74b140-3506-4139-b161-91d2daa5bd8b" xlink:to="loc_us-gaap_EmbeddedDerivativeFinancialInstrumentsMember_84d28a3b-44b6-4eab-aa0a-1d41884a81aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_412c0bd1-0c4c-45dc-885d-25bc07ef1e1d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fa74b140-3506-4139-b161-91d2daa5bd8b" xlink:to="loc_us-gaap_ForeignExchangeContractMember_412c0bd1-0c4c-45dc-885d-25bc07ef1e1d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_712274b6-c66f-4069-9f21-3f70ab8ea1b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_a7f83fd8-d201-48d5-a28d-2e845eadbc8f" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_712274b6-c66f-4069-9f21-3f70ab8ea1b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_6bd71143-31cf-49a0-a832-5629d08fb531" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_a7f83fd8-d201-48d5-a28d-2e845eadbc8f" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_6bd71143-31cf-49a0-a832-5629d08fb531" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossRealizedAfterTax_1be1fb6d-394b-4d58-9539-0b624be3df3a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyTransactionGainLossRealizedAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_a7f83fd8-d201-48d5-a28d-2e845eadbc8f" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossRealizedAfterTax_1be1fb6d-394b-4d58-9539-0b624be3df3a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealizedAfterTax_905b5c8e-9e49-46c7-84d6-909b6ba58c3b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealizedAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_a7f83fd8-d201-48d5-a28d-2e845eadbc8f" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealizedAfterTax_905b5c8e-9e49-46c7-84d6-909b6ba58c3b" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/FinancialInstrumentsandFinancialRiskScheduleofFairValueAssetsandLiabilitiesMeasuredonRecurringBasisDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#FinancialInstrumentsandFinancialRiskScheduleofFairValueAssetsandLiabilitiesMeasuredonRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/FinancialInstrumentsandFinancialRiskScheduleofFairValueAssetsandLiabilitiesMeasuredonRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_7e6510ae-0e98-4ba5-b1f7-d6c2e404af67" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_dc0529a5-4b6a-45b6-ad1c-c95de3f94552" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_7e6510ae-0e98-4ba5-b1f7-d6c2e404af67" xlink:to="loc_us-gaap_DerivativeTable_dc0529a5-4b6a-45b6-ad1c-c95de3f94552" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_9cac119a-2165-4a4d-99ba-db3d985ba03f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_dc0529a5-4b6a-45b6-ad1c-c95de3f94552" xlink:to="loc_us-gaap_HedgingDesignationAxis_9cac119a-2165-4a4d-99ba-db3d985ba03f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_9cac119a-2165-4a4d-99ba-db3d985ba03f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_9cac119a-2165-4a4d-99ba-db3d985ba03f" xlink:to="loc_us-gaap_HedgingDesignationDomain_9cac119a-2165-4a4d-99ba-db3d985ba03f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_184bf450-5982-462f-8d69-53c1c3b8939b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_9cac119a-2165-4a4d-99ba-db3d985ba03f" xlink:to="loc_us-gaap_HedgingDesignationDomain_184bf450-5982-462f-8d69-53c1c3b8939b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_b7107f7d-4ae0-4be9-81b6-cf226c1182eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_184bf450-5982-462f-8d69-53c1c3b8939b" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_b7107f7d-4ae0-4be9-81b6-cf226c1182eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_cdcd9e07-0ee3-4196-9360-92393428408f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_184bf450-5982-462f-8d69-53c1c3b8939b" xlink:to="loc_us-gaap_NondesignatedMember_cdcd9e07-0ee3-4196-9360-92393428408f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_4308e92c-119d-4063-815e-e1d431eebec0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_dc0529a5-4b6a-45b6-ad1c-c95de3f94552" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_4308e92c-119d-4063-815e-e1d431eebec0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_4308e92c-119d-4063-815e-e1d431eebec0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_4308e92c-119d-4063-815e-e1d431eebec0" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_4308e92c-119d-4063-815e-e1d431eebec0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e110cc5f-f8e0-4360-9a1f-f614192e4223" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_4308e92c-119d-4063-815e-e1d431eebec0" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e110cc5f-f8e0-4360-9a1f-f614192e4223" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_b39e75bb-15c1-41c6-a957-5a1d5b238e4e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e110cc5f-f8e0-4360-9a1f-f614192e4223" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_b39e75bb-15c1-41c6-a957-5a1d5b238e4e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_8f357f58-772c-4ec1-9882-c65850cbc647" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_b39e75bb-15c1-41c6-a957-5a1d5b238e4e" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_8f357f58-772c-4ec1-9882-c65850cbc647" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_e9d0534b-72e8-4f71-bdb4-0862ebd27e70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_dc0529a5-4b6a-45b6-ad1c-c95de3f94552" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_e9d0534b-72e8-4f71-bdb4-0862ebd27e70" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_e9d0534b-72e8-4f71-bdb4-0862ebd27e70_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_e9d0534b-72e8-4f71-bdb4-0862ebd27e70" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_e9d0534b-72e8-4f71-bdb4-0862ebd27e70_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_6f13e2f7-0720-4ffa-8ce9-23e759e5b670" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_e9d0534b-72e8-4f71-bdb4-0862ebd27e70" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_6f13e2f7-0720-4ffa-8ce9-23e759e5b670" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_fb8fc3ea-4c64-4cae-a4e4-7d760a2cd22c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_6f13e2f7-0720-4ffa-8ce9-23e759e5b670" xlink:to="loc_us-gaap_InterestRateSwapMember_fb8fc3ea-4c64-4cae-a4e4-7d760a2cd22c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCapMember_815b8673-307d-49e9-9402-7dfeecd5071c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateCapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_6f13e2f7-0720-4ffa-8ce9-23e759e5b670" xlink:to="loc_us-gaap_InterestRateCapMember_815b8673-307d-49e9-9402-7dfeecd5071c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_1b6e779e-7aeb-4bb4-ac59-9381acc74e24" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_6f13e2f7-0720-4ffa-8ce9-23e759e5b670" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_1b6e779e-7aeb-4bb4-ac59-9381acc74e24" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmbeddedDerivativeFinancialInstrumentsMember_8b9f2240-a0fb-4f52-99d5-413e68a9be1d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmbeddedDerivativeFinancialInstrumentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_6f13e2f7-0720-4ffa-8ce9-23e759e5b670" xlink:to="loc_us-gaap_EmbeddedDerivativeFinancialInstrumentsMember_8b9f2240-a0fb-4f52-99d5-413e68a9be1d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_77a86dd9-c52e-4a06-8bbe-328ffa36da85" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_dc0529a5-4b6a-45b6-ad1c-c95de3f94552" xlink:to="loc_us-gaap_DebtInstrumentAxis_77a86dd9-c52e-4a06-8bbe-328ffa36da85" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_77a86dd9-c52e-4a06-8bbe-328ffa36da85_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_77a86dd9-c52e-4a06-8bbe-328ffa36da85" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_77a86dd9-c52e-4a06-8bbe-328ffa36da85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_9f63d27a-a6bd-47ca-bc44-6633640f9a70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_77a86dd9-c52e-4a06-8bbe-328ffa36da85" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_9f63d27a-a6bd-47ca-bc44-6633640f9a70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TermLoanDue2031Member_29043eff-38da-4979-a55b-ff63c2c041e2" xlink:href="shc-20241231.xsd#shc_TermLoanDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_9f63d27a-a6bd-47ca-bc44-6633640f9a70" xlink:to="loc_shc_TermLoanDue2031Member_29043eff-38da-4979-a55b-ff63c2c041e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SeniorSecuredNotesDue2031Member_ef36a959-5cf4-426d-8b7b-dd5f10db1a92" xlink:href="shc-20241231.xsd#shc_SeniorSecuredNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_9f63d27a-a6bd-47ca-bc44-6633640f9a70" xlink:to="loc_shc_SeniorSecuredNotesDue2031Member_ef36a959-5cf4-426d-8b7b-dd5f10db1a92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TermLoanDue2026Member_4a171134-7608-4e31-ac28-aa09dddaf860" xlink:href="shc-20241231.xsd#shc_TermLoanDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_9f63d27a-a6bd-47ca-bc44-6633640f9a70" xlink:to="loc_shc_TermLoanDue2026Member_4a171134-7608-4e31-ac28-aa09dddaf860" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_TermLoanBDue2026Member_713a72c9-b8e3-4b87-a321-0a2b121d7a27" xlink:href="shc-20241231.xsd#shc_TermLoanBDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_9f63d27a-a6bd-47ca-bc44-6633640f9a70" xlink:to="loc_shc_TermLoanBDue2026Member_713a72c9-b8e3-4b87-a321-0a2b121d7a27" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_FinanceLeaseLiabilityMember_c4ccd042-ea15-4a7b-bcce-54a5ffa68b21" xlink:href="shc-20241231.xsd#shc_FinanceLeaseLiabilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_9f63d27a-a6bd-47ca-bc44-6633640f9a70" xlink:to="loc_shc_FinanceLeaseLiabilityMember_c4ccd042-ea15-4a7b-bcce-54a5ffa68b21" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_3cfed03b-a0a6-4cd2-a24a-7dfc7561cbd0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_dc0529a5-4b6a-45b6-ad1c-c95de3f94552" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_3cfed03b-a0a6-4cd2-a24a-7dfc7561cbd0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3cfed03b-a0a6-4cd2-a24a-7dfc7561cbd0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_3cfed03b-a0a6-4cd2-a24a-7dfc7561cbd0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3cfed03b-a0a6-4cd2-a24a-7dfc7561cbd0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_dc13d49f-0486-4711-afb6-3e0d371cf700" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_3cfed03b-a0a6-4cd2-a24a-7dfc7561cbd0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_dc13d49f-0486-4711-afb6-3e0d371cf700" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_f965b1b6-d73b-4661-9035-4a88e474f8b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_dc13d49f-0486-4711-afb6-3e0d371cf700" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_f965b1b6-d73b-4661-9035-4a88e474f8b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_002ef34e-b72c-4c92-b9ce-bd2bc26e6d03" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_dc13d49f-0486-4711-afb6-3e0d371cf700" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_002ef34e-b72c-4c92-b9ce-bd2bc26e6d03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_e62be35c-9165-419e-b56e-81dcc3c72262" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_dc13d49f-0486-4711-afb6-3e0d371cf700" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_e62be35c-9165-419e-b56e-81dcc3c72262" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_f60cff20-1cd2-4b3e-82d0-bfaaf2dd7f8a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7e6510ae-0e98-4ba5-b1f7-d6c2e404af67" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_f60cff20-1cd2-4b3e-82d0-bfaaf2dd7f8a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_46391059-bd10-46f0-afd9-46a1e172f7d9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7e6510ae-0e98-4ba5-b1f7-d6c2e404af67" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_46391059-bd10-46f0-afd9-46a1e172f7d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_LongTermDebtCurrentMaturitiesFairValue_324780fa-811f-439e-bf89-97866df0f394" xlink:href="shc-20241231.xsd#shc_LongTermDebtCurrentMaturitiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7e6510ae-0e98-4ba5-b1f7-d6c2e404af67" xlink:to="loc_shc_LongTermDebtCurrentMaturitiesFairValue_324780fa-811f-439e-bf89-97866df0f394" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_fc4ec8af-52eb-42b4-ad7b-b11abac900af" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7e6510ae-0e98-4ba5-b1f7-d6c2e404af67" xlink:to="loc_us-gaap_LongTermDebtFairValue_fc4ec8af-52eb-42b4-ad7b-b11abac900af" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/SegmentandGeographicInformationAdditionalInformationDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#SegmentandGeographicInformationAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/SegmentandGeographicInformationAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_cc357c0f-c9f3-4f69-b13c-6cc86ad7e6f1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_152a6273-e700-43ae-b777-1d84eee84928" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_cc357c0f-c9f3-4f69-b13c-6cc86ad7e6f1" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_152a6273-e700-43ae-b777-1d84eee84928" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_1760e698-7a87-4a44-81d1-6738582b33f1" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_152a6273-e700-43ae-b777-1d84eee84928" xlink:to="loc_srt_ConsolidationItemsAxis_1760e698-7a87-4a44-81d1-6738582b33f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_1760e698-7a87-4a44-81d1-6738582b33f1_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_1760e698-7a87-4a44-81d1-6738582b33f1" xlink:to="loc_srt_ConsolidationItemsDomain_1760e698-7a87-4a44-81d1-6738582b33f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_67c2a5ba-b753-4e7e-b227-367630dbe2e5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_1760e698-7a87-4a44-81d1-6738582b33f1" xlink:to="loc_srt_ConsolidationItemsDomain_67c2a5ba-b753-4e7e-b227-367630dbe2e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_e6ced53a-4bca-4302-9196-8ee4289f65da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_67c2a5ba-b753-4e7e-b227-367630dbe2e5" xlink:to="loc_us-gaap_OperatingSegmentsMember_e6ced53a-4bca-4302-9196-8ee4289f65da" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_d3da2653-a398-4e70-a6f6-5837fd4d625e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_152a6273-e700-43ae-b777-1d84eee84928" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_d3da2653-a398-4e70-a6f6-5837fd4d625e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_d3da2653-a398-4e70-a6f6-5837fd4d625e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_d3da2653-a398-4e70-a6f6-5837fd4d625e" xlink:to="loc_us-gaap_SegmentDomain_d3da2653-a398-4e70-a6f6-5837fd4d625e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_abcd0e66-1dbd-4006-a1dd-7be53bcee774" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_d3da2653-a398-4e70-a6f6-5837fd4d625e" xlink:to="loc_us-gaap_SegmentDomain_abcd0e66-1dbd-4006-a1dd-7be53bcee774" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NordionMember_c5d3e575-73af-4264-8b09-664001d3733a" xlink:href="shc-20241231.xsd#shc_NordionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_abcd0e66-1dbd-4006-a1dd-7be53bcee774" xlink:to="loc_shc_NordionMember_c5d3e575-73af-4264-8b09-664001d3733a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_6b0df04c-4179-4089-b29c-b80da179a1f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_152a6273-e700-43ae-b777-1d84eee84928" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_6b0df04c-4179-4089-b29c-b80da179a1f0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_6b0df04c-4179-4089-b29c-b80da179a1f0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_6b0df04c-4179-4089-b29c-b80da179a1f0" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_6b0df04c-4179-4089-b29c-b80da179a1f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_3969d901-043a-409a-9886-a23cdf98813e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_6b0df04c-4179-4089-b29c-b80da179a1f0" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_3969d901-043a-409a-9886-a23cdf98813e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_a665911f-e78f-436b-8e63-4a698eabd3d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_3969d901-043a-409a-9886-a23cdf98813e" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_a665911f-e78f-436b-8e63-4a698eabd3d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_6bac194f-0fbc-4404-bc1f-32d07048080a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_152a6273-e700-43ae-b777-1d84eee84928" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_6bac194f-0fbc-4404-bc1f-32d07048080a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_6bac194f-0fbc-4404-bc1f-32d07048080a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_6bac194f-0fbc-4404-bc1f-32d07048080a" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_6bac194f-0fbc-4404-bc1f-32d07048080a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_81e4ec43-f9e4-4612-ade3-9e2fa7ddfc46" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_6bac194f-0fbc-4404-bc1f-32d07048080a" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_81e4ec43-f9e4-4612-ade3-9e2fa7ddfc46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_7bb4071a-a065-472e-b763-e7d3ae303695" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_81e4ec43-f9e4-4612-ade3-9e2fa7ddfc46" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_7bb4071a-a065-472e-b763-e7d3ae303695" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_1290f2c7-fd13-44b7-8485-ca2556b96faf" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_152a6273-e700-43ae-b777-1d84eee84928" xlink:to="loc_srt_MajorCustomersAxis_1290f2c7-fd13-44b7-8485-ca2556b96faf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_1290f2c7-fd13-44b7-8485-ca2556b96faf_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_1290f2c7-fd13-44b7-8485-ca2556b96faf" xlink:to="loc_srt_NameOfMajorCustomerDomain_1290f2c7-fd13-44b7-8485-ca2556b96faf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_573471ad-5975-489a-be6a-9b81f2b787ee" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_1290f2c7-fd13-44b7-8485-ca2556b96faf" xlink:to="loc_srt_NameOfMajorCustomerDomain_573471ad-5975-489a-be6a-9b81f2b787ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_CustomerOneMember_70d9002d-497f-4d3a-9c8d-94e3192e114d" xlink:href="shc-20241231.xsd#shc_CustomerOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_573471ad-5975-489a-be6a-9b81f2b787ee" xlink:to="loc_shc_CustomerOneMember_70d9002d-497f-4d3a-9c8d-94e3192e114d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_CustomerTwoMember_4b11df38-f6c5-4f1a-ba33-e96bb45c16ce" xlink:href="shc-20241231.xsd#shc_CustomerTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_573471ad-5975-489a-be6a-9b81f2b787ee" xlink:to="loc_shc_CustomerTwoMember_4b11df38-f6c5-4f1a-ba33-e96bb45c16ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_CustomerThreeMember_b39be313-3629-411f-99ce-408a063ac74a" xlink:href="shc-20241231.xsd#shc_CustomerThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_573471ad-5975-489a-be6a-9b81f2b787ee" xlink:to="loc_shc_CustomerThreeMember_b39be313-3629-411f-99ce-408a063ac74a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_CustomerFourMember_9ae9242a-9045-46ba-879c-e7321f07858d" xlink:href="shc-20241231.xsd#shc_CustomerFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_573471ad-5975-489a-be6a-9b81f2b787ee" xlink:to="loc_shc_CustomerFourMember_9ae9242a-9045-46ba-879c-e7321f07858d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_CustomerFiveMember_3da1e259-ad33-4b19-8db8-f114ee099036" xlink:href="shc-20241231.xsd#shc_CustomerFiveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_573471ad-5975-489a-be6a-9b81f2b787ee" xlink:to="loc_shc_CustomerFiveMember_3da1e259-ad33-4b19-8db8-f114ee099036" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_c5caa2bc-4c7c-418a-b2c7-549f6c2bcd56" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_cc357c0f-c9f3-4f69-b13c-6cc86ad7e6f1" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_c5caa2bc-4c7c-418a-b2c7-549f6c2bcd56" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/SegmentandGeographicInformationScheduleofSegmentOperatingResultsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#SegmentandGeographicInformationScheduleofSegmentOperatingResultsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/SegmentandGeographicInformationScheduleofSegmentOperatingResultsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_4b05bef0-f41a-4a10-b71e-d57c628a91a9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_9edb6bca-fe2b-44b6-a952-dea811202cd5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4b05bef0-f41a-4a10-b71e-d57c628a91a9" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_9edb6bca-fe2b-44b6-a952-dea811202cd5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_249e1fc1-aada-42cc-a974-356055a369fb" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_9edb6bca-fe2b-44b6-a952-dea811202cd5" xlink:to="loc_srt_ConsolidationItemsAxis_249e1fc1-aada-42cc-a974-356055a369fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_249e1fc1-aada-42cc-a974-356055a369fb_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_249e1fc1-aada-42cc-a974-356055a369fb" xlink:to="loc_srt_ConsolidationItemsDomain_249e1fc1-aada-42cc-a974-356055a369fb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_92f54571-ab83-4e83-8182-b061bae4c808" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_249e1fc1-aada-42cc-a974-356055a369fb" xlink:to="loc_srt_ConsolidationItemsDomain_92f54571-ab83-4e83-8182-b061bae4c808" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_814b86ed-2dc9-4415-a55f-9badc45fdb1f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_92f54571-ab83-4e83-8182-b061bae4c808" xlink:to="loc_us-gaap_OperatingSegmentsMember_814b86ed-2dc9-4415-a55f-9badc45fdb1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_83642a8e-b49a-4f9e-880c-4f474c6a9e78" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_92f54571-ab83-4e83-8182-b061bae4c808" xlink:to="loc_us-gaap_CorporateNonSegmentMember_83642a8e-b49a-4f9e-880c-4f474c6a9e78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_2e10f64d-fb51-48a2-8444-62b2fb0304ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_92f54571-ab83-4e83-8182-b061bae4c808" xlink:to="loc_us-gaap_IntersegmentEliminationMember_2e10f64d-fb51-48a2-8444-62b2fb0304ad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_49737b26-ee8b-4835-bbbb-f1a50d9e90f9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_9edb6bca-fe2b-44b6-a952-dea811202cd5" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_49737b26-ee8b-4835-bbbb-f1a50d9e90f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_49737b26-ee8b-4835-bbbb-f1a50d9e90f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_49737b26-ee8b-4835-bbbb-f1a50d9e90f9" xlink:to="loc_us-gaap_SegmentDomain_49737b26-ee8b-4835-bbbb-f1a50d9e90f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_ebf9fd83-ef15-47ef-b476-bbe4efda8fc2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_49737b26-ee8b-4835-bbbb-f1a50d9e90f9" xlink:to="loc_us-gaap_SegmentDomain_ebf9fd83-ef15-47ef-b476-bbe4efda8fc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SterigenicsMember_48eed891-6d76-4a0e-8fb5-caf546077b73" xlink:href="shc-20241231.xsd#shc_SterigenicsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_ebf9fd83-ef15-47ef-b476-bbe4efda8fc2" xlink:to="loc_shc_SterigenicsMember_48eed891-6d76-4a0e-8fb5-caf546077b73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NordionMember_81f7250d-c6ff-4d28-a643-e40bb745cbab" xlink:href="shc-20241231.xsd#shc_NordionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_ebf9fd83-ef15-47ef-b476-bbe4efda8fc2" xlink:to="loc_shc_NordionMember_81f7250d-c6ff-4d28-a643-e40bb745cbab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NelsonLabsMember_ad367366-5a34-42c6-90ea-b867f79056ca" xlink:href="shc-20241231.xsd#shc_NelsonLabsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_ebf9fd83-ef15-47ef-b476-bbe4efda8fc2" xlink:to="loc_shc_NelsonLabsMember_ad367366-5a34-42c6-90ea-b867f79056ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_660584f2-c90e-42f9-9f2b-9c9300b36960" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4b05bef0-f41a-4a10-b71e-d57c628a91a9" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_660584f2-c90e-42f9-9f2b-9c9300b36960" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_3dd6aa14-39a5-4f73-9209-ce7cfe358ae6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4b05bef0-f41a-4a10-b71e-d57c628a91a9" xlink:to="loc_us-gaap_OperatingExpenses_3dd6aa14-39a5-4f73-9209-ce7cfe358ae6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_cf621d22-2912-490b-9bcb-374a99772af6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4b05bef0-f41a-4a10-b71e-d57c628a91a9" xlink:to="loc_us-gaap_OperatingIncomeLoss_cf621d22-2912-490b-9bcb-374a99772af6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_86085e68-cfd7-46df-8de6-07472ef4c951" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentExpenditureAdditionToLongLivedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4b05bef0-f41a-4a10-b71e-d57c628a91a9" xlink:to="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_86085e68-cfd7-46df-8de6-07472ef4c951" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/SegmentandGeographicInformationScheduleofReconciliationofReportableSegmentAmountsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#SegmentandGeographicInformationScheduleofReconciliationofReportableSegmentAmountsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/SegmentandGeographicInformationScheduleofReconciliationofReportableSegmentAmountsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_459ede5f-6e78-4ae2-97a9-48bfe13badda" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_459ede5f-6e78-4ae2-97a9-48bfe13badda" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_e7a6f66d-fde2-4e81-96f9-ce234429f199" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_459ede5f-6e78-4ae2-97a9-48bfe13badda" xlink:to="loc_srt_ConsolidationItemsAxis_e7a6f66d-fde2-4e81-96f9-ce234429f199" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_e7a6f66d-fde2-4e81-96f9-ce234429f199_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_e7a6f66d-fde2-4e81-96f9-ce234429f199" xlink:to="loc_srt_ConsolidationItemsDomain_e7a6f66d-fde2-4e81-96f9-ce234429f199_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_32933d80-2a03-41f8-9c97-8887f9392abd" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_e7a6f66d-fde2-4e81-96f9-ce234429f199" xlink:to="loc_srt_ConsolidationItemsDomain_32933d80-2a03-41f8-9c97-8887f9392abd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_cf7f975a-2aa9-4533-8645-b2aefc9f7b47" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_32933d80-2a03-41f8-9c97-8887f9392abd" xlink:to="loc_us-gaap_OperatingSegmentsMember_cf7f975a-2aa9-4533-8645-b2aefc9f7b47" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_3dc34281-335e-49f8-81dc-65ec5537808d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_32933d80-2a03-41f8-9c97-8887f9392abd" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_3dc34281-335e-49f8-81dc-65ec5537808d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_01af4344-6a56-4535-be60-9ded1f01cc13" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_459ede5f-6e78-4ae2-97a9-48bfe13badda" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_01af4344-6a56-4535-be60-9ded1f01cc13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_01af4344-6a56-4535-be60-9ded1f01cc13_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_01af4344-6a56-4535-be60-9ded1f01cc13" xlink:to="loc_us-gaap_SegmentDomain_01af4344-6a56-4535-be60-9ded1f01cc13_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_6ec4b346-add8-4385-a7db-b0f9e434f62e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_01af4344-6a56-4535-be60-9ded1f01cc13" xlink:to="loc_us-gaap_SegmentDomain_6ec4b346-add8-4385-a7db-b0f9e434f62e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_NordionMember_a60a8212-5869-4e2b-b7db-e430892c2aa8" xlink:href="shc-20241231.xsd#shc_NordionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6ec4b346-add8-4385-a7db-b0f9e434f62e" xlink:to="loc_shc_NordionMember_a60a8212-5869-4e2b-b7db-e430892c2aa8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_344dfc6d-c53c-4eb0-97ba-da5aa5542f9b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_459ede5f-6e78-4ae2-97a9-48bfe13badda" xlink:to="loc_srt_LitigationCaseAxis_344dfc6d-c53c-4eb0-97ba-da5aa5542f9b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_344dfc6d-c53c-4eb0-97ba-da5aa5542f9b_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_344dfc6d-c53c-4eb0-97ba-da5aa5542f9b" xlink:to="loc_srt_LitigationCaseTypeDomain_344dfc6d-c53c-4eb0-97ba-da5aa5542f9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_5266f5e0-b021-48c4-a3ab-a9fd2021b8e1" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_344dfc6d-c53c-4eb0-97ba-da5aa5542f9b" xlink:to="loc_srt_LitigationCaseTypeDomain_5266f5e0-b021-48c4-a3ab-a9fd2021b8e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationIllinoisMember_60de8ede-5635-4f66-ba32-c4878eafd9b5" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationIllinoisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_5266f5e0-b021-48c4-a3ab-a9fd2021b8e1" xlink:to="loc_shc_EthyleneOxideTortLitigationIllinoisMember_60de8ede-5635-4f66-ba32-c4878eafd9b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_EthyleneOxideTortLitigationGeorgiaMember_41f63503-eaf2-4b8b-ab5d-598464aae265" xlink:href="shc-20241231.xsd#shc_EthyleneOxideTortLitigationGeorgiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_5266f5e0-b021-48c4-a3ab-a9fd2021b8e1" xlink:to="loc_shc_EthyleneOxideTortLitigationGeorgiaMember_41f63503-eaf2-4b8b-ab5d-598464aae265" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_1e1265b7-1472-4dba-9e66-ecf2ef2e1d6e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_459ede5f-6e78-4ae2-97a9-48bfe13badda" xlink:to="loc_srt_StatementGeographicalAxis_1e1265b7-1472-4dba-9e66-ecf2ef2e1d6e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_1e1265b7-1472-4dba-9e66-ecf2ef2e1d6e_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_1e1265b7-1472-4dba-9e66-ecf2ef2e1d6e" xlink:to="loc_srt_SegmentGeographicalDomain_1e1265b7-1472-4dba-9e66-ecf2ef2e1d6e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_4e727602-9f55-4229-8b47-b6cbacdbb291" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_1e1265b7-1472-4dba-9e66-ecf2ef2e1d6e" xlink:to="loc_srt_SegmentGeographicalDomain_4e727602-9f55-4229-8b47-b6cbacdbb291" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_GA_1666eb9c-d78b-45a9-bb0c-b6ebbb34a840" xlink:href="https://xbrl.sec.gov/stpr/2024/stpr-2024.xsd#stpr_GA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_4e727602-9f55-4229-8b47-b6cbacdbb291" xlink:to="loc_stpr_GA_1666eb9c-d78b-45a9-bb0c-b6ebbb34a840" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_a779bdc5-0fe5-41b4-babe-620e9cdf0db7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_459ede5f-6e78-4ae2-97a9-48bfe13badda" xlink:to="loc_us-gaap_LitigationStatusAxis_a779bdc5-0fe5-41b4-babe-620e9cdf0db7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_a779bdc5-0fe5-41b4-babe-620e9cdf0db7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_a779bdc5-0fe5-41b4-babe-620e9cdf0db7" xlink:to="loc_us-gaap_LitigationStatusDomain_a779bdc5-0fe5-41b4-babe-620e9cdf0db7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_82f5b01d-0577-4f17-ac44-715de10943a9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_a779bdc5-0fe5-41b4-babe-620e9cdf0db7" xlink:to="loc_us-gaap_LitigationStatusDomain_82f5b01d-0577-4f17-ac44-715de10943a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_1e33e615-6d96-4f8e-9453-cea278a4c1d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_82f5b01d-0577-4f17-ac44-715de10943a9" xlink:to="loc_us-gaap_PendingLitigationMember_1e33e615-6d96-4f8e-9453-cea278a4c1d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_95f731e5-51ba-4e05-81f0-7c2f7b06a782" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_459ede5f-6e78-4ae2-97a9-48bfe13badda" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_95f731e5-51ba-4e05-81f0-7c2f7b06a782" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_95f731e5-51ba-4e05-81f0-7c2f7b06a782_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_95f731e5-51ba-4e05-81f0-7c2f7b06a782" xlink:to="loc_us-gaap_LossContingencyNatureDomain_95f731e5-51ba-4e05-81f0-7c2f7b06a782_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_f064d537-86cd-4c88-9770-c0278c77f692" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_95f731e5-51ba-4e05-81f0-7c2f7b06a782" xlink:to="loc_us-gaap_LossContingencyNatureDomain_f064d537-86cd-4c88-9770-c0278c77f692" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PersonalInjuryAndWrongfulDeathMember_5423e850-81bb-4479-86e0-3e81d0ce5c78" xlink:href="shc-20241231.xsd#shc_PersonalInjuryAndWrongfulDeathMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_f064d537-86cd-4c88-9770-c0278c77f692" xlink:to="loc_shc_PersonalInjuryAndWrongfulDeathMember_5423e850-81bb-4479-86e0-3e81d0ce5c78" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_5dc3f621-5bd8-4115-a1b5-2e0ddd396bba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_459ede5f-6e78-4ae2-97a9-48bfe13badda" xlink:to="loc_us-gaap_CreditFacilityAxis_5dc3f621-5bd8-4115-a1b5-2e0ddd396bba" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_5dc3f621-5bd8-4115-a1b5-2e0ddd396bba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_5dc3f621-5bd8-4115-a1b5-2e0ddd396bba" xlink:to="loc_us-gaap_CreditFacilityDomain_5dc3f621-5bd8-4115-a1b5-2e0ddd396bba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_80578928-f1d0-4bd4-8482-e2577fcf07a2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_5dc3f621-5bd8-4115-a1b5-2e0ddd396bba" xlink:to="loc_us-gaap_CreditFacilityDomain_80578928-f1d0-4bd4-8482-e2577fcf07a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_a939cccf-9feb-4293-8950-1d3c3f6c31e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_80578928-f1d0-4bd4-8482-e2577fcf07a2" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_a939cccf-9feb-4293-8950-1d3c3f6c31e4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_5535d0f7-0e98-43e5-9fe1-27f1ed06fd13" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_459ede5f-6e78-4ae2-97a9-48bfe13badda" xlink:to="loc_us-gaap_HedgingDesignationAxis_5535d0f7-0e98-43e5-9fe1-27f1ed06fd13" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_5535d0f7-0e98-43e5-9fe1-27f1ed06fd13_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_5535d0f7-0e98-43e5-9fe1-27f1ed06fd13" xlink:to="loc_us-gaap_HedgingDesignationDomain_5535d0f7-0e98-43e5-9fe1-27f1ed06fd13_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_acd4941a-98a8-4c95-8b61-00fa51154099" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_5535d0f7-0e98-43e5-9fe1-27f1ed06fd13" xlink:to="loc_us-gaap_HedgingDesignationDomain_acd4941a-98a8-4c95-8b61-00fa51154099" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_b8ce72c1-e873-4311-ada5-d8982d892e00" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_acd4941a-98a8-4c95-8b61-00fa51154099" xlink:to="loc_us-gaap_NondesignatedMember_b8ce72c1-e873-4311-ada5-d8982d892e00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_978d0548-10e0-4fb2-ab45-cbcfb6b6c4e3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_OperatingIncomeLoss_978d0548-10e0-4fb2-ab45-cbcfb6b6c4e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_f7897fc1-21b5-44d4-821d-c61bb3f68443" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_InterestExpense_f7897fc1-21b5-44d4-821d-c61bb3f68443" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_DepreciationAmortizationAndAdditions_58b51cbb-94e6-4b43-ae2f-d7c2d0ff1082" xlink:href="shc-20241231.xsd#shc_DepreciationAmortizationAndAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_shc_DepreciationAmortizationAndAdditions_58b51cbb-94e6-4b43-ae2f-d7c2d0ff1082" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_b13e7cce-989f-4841-b5e2-86459b2e8c9d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_ShareBasedCompensation_b13e7cce-989f-4841-b5e2-86459b2e8c9d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_GainLossOnRefinancingOfDebt_f5b5d26f-a03a-48bb-a017-1b363dea6760" xlink:href="shc-20241231.xsd#shc_GainLossOnRefinancingOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_shc_GainLossOnRefinancingOfDebt_f5b5d26f-a03a-48bb-a017-1b363dea6760" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_ForeignCurrencyGainLossAndGainLossOnEmbeddedDerivative_03482010-c819-4ea9-ae08-1da26865918c" xlink:href="shc-20241231.xsd#shc_ForeignCurrencyGainLossAndGainLossOnEmbeddedDerivative"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_shc_ForeignCurrencyGainLossAndGainLossOnEmbeddedDerivative_03482010-c819-4ea9-ae08-1da26865918c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRestructuringCosts_85e70c59-b32a-4d63-bb80-ab2fdb527ea4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherRestructuringCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_OtherRestructuringCosts_85e70c59-b32a-4d63-bb80-ab2fdb527ea4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_9ef4cc6e-96e9-4d1b-9a62-616a451bb3ca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_9ef4cc6e-96e9-4d1b-9a62-616a451bb3ca" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementExpense_1fe9ae31-daf1-47d3-ad60-842f1d45f0b1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationSettlementExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_LitigationSettlementExpense_1fe9ae31-daf1-47d3-ad60-842f1d45f0b1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossRelatedToLitigationSettlement_64233da6-4bf5-4b6a-b38b-b4e5cd9a30ab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainLossRelatedToLitigationSettlement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_GainLossRelatedToLitigationSettlement_64233da6-4bf5-4b6a-b38b-b4e5cd9a30ab" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_SecondaryOfferingCostsAndOtherActivities_b0812e21-b70c-4e09-a7a2-56666a584f1f" xlink:href="shc-20241231.xsd#shc_SecondaryOfferingCostsAndOtherActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_shc_SecondaryOfferingCostsAndOtherActivities_b0812e21-b70c-4e09-a7a2-56666a584f1f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationAccretionExpense_9c8a56a0-1298-4136-9430-cb58a7676bb2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetRetirementObligationAccretionExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_AssetRetirementObligationAccretionExpense_9c8a56a0-1298-4136-9430-cb58a7676bb2" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_a9482524-4a30-4c72-9fad-7ed381b35b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_a9482524-4a30-4c72-9fad-7ed381b35b9d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_2f759a31-ba73-49e0-a2a9-07578c910415" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_2f759a31-ba73-49e0-a2a9-07578c910415" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_7d4a7c03-24c5-4f31-81f2-bfe87785a581" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_7d4a7c03-24c5-4f31-81f2-bfe87785a581" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtRestructuringCosts_fe7edbda-c420-4d36-8267-9884950fb1f4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsOfDebtRestructuringCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_PaymentsOfDebtRestructuringCosts_fe7edbda-c420-4d36-8267-9884950fb1f4" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_CancellationFeeReceivedForLeaseTermination_328b213d-a528-4f3d-9cb6-5d2fec7b37eb" xlink:href="shc-20241231.xsd#shc_CancellationFeeReceivedForLeaseTermination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_shc_CancellationFeeReceivedForLeaseTermination_328b213d-a528-4f3d-9cb6-5d2fec7b37eb" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_9fb33c21-9095-4025-9755-aef20571ccb0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_faf114df-4583-42ea-828d-2eea4329681b" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_9fb33c21-9095-4025-9755-aef20571ccb0" xlink:type="arc" order="17"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/SegmentandGeographicInformationScheduleofRevenuesDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#SegmentandGeographicInformationScheduleofRevenuesDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/SegmentandGeographicInformationScheduleofRevenuesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_9819bc7c-cd27-41fb-93ed-bd10820e030a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_30c75dcf-ac46-48f8-9230-7363d32bcc65" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9819bc7c-cd27-41fb-93ed-bd10820e030a" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_30c75dcf-ac46-48f8-9230-7363d32bcc65" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_244ef207-1d97-4312-bc0d-8c3ea611f01f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_30c75dcf-ac46-48f8-9230-7363d32bcc65" xlink:to="loc_srt_StatementGeographicalAxis_244ef207-1d97-4312-bc0d-8c3ea611f01f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_244ef207-1d97-4312-bc0d-8c3ea611f01f_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_244ef207-1d97-4312-bc0d-8c3ea611f01f" xlink:to="loc_srt_SegmentGeographicalDomain_244ef207-1d97-4312-bc0d-8c3ea611f01f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_14598235-9a02-4afd-a854-40d4b7fa6b97" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_244ef207-1d97-4312-bc0d-8c3ea611f01f" xlink:to="loc_srt_SegmentGeographicalDomain_14598235-9a02-4afd-a854-40d4b7fa6b97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_3825faa7-d92d-4052-9786-952f7a041dab" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_14598235-9a02-4afd-a854-40d4b7fa6b97" xlink:to="loc_country_US_3825faa7-d92d-4052-9786-952f7a041dab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_9cbaadd6-5bb9-4a94-9681-7eeeaddf708b" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_14598235-9a02-4afd-a854-40d4b7fa6b97" xlink:to="loc_country_CA_9cbaadd6-5bb9-4a94-9681-7eeeaddf708b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EuropeMember_394befae-e2d1-42b7-94f2-fa6c7030ec14" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_EuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_14598235-9a02-4afd-a854-40d4b7fa6b97" xlink:to="loc_srt_EuropeMember_394befae-e2d1-42b7-94f2-fa6c7030ec14" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_OtherGeographicalAreasMember_a474f087-0897-497b-b20c-9b59607eefa8" xlink:href="shc-20241231.xsd#shc_OtherGeographicalAreasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_14598235-9a02-4afd-a854-40d4b7fa6b97" xlink:to="loc_shc_OtherGeographicalAreasMember_a474f087-0897-497b-b20c-9b59607eefa8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaMember_6a5a8f1b-4281-494d-8fe9-645c1e7dfb9f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_AsiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_14598235-9a02-4afd-a854-40d4b7fa6b97" xlink:to="loc_srt_AsiaMember_6a5a8f1b-4281-494d-8fe9-645c1e7dfb9f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LatinAmericaMember_1a7acad9-8418-426e-8970-994ef33efa7a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LatinAmericaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_14598235-9a02-4afd-a854-40d4b7fa6b97" xlink:to="loc_srt_LatinAmericaMember_1a7acad9-8418-426e-8970-994ef33efa7a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_dd991653-61c7-4373-b1f9-8aca12ca64b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9819bc7c-cd27-41fb-93ed-bd10820e030a" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_dd991653-61c7-4373-b1f9-8aca12ca64b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PercentOfRevenueFromContractWithCustomerExcludingAssessedTax_c53f7fa1-2816-4822-bc03-76d8c44ad461" xlink:href="shc-20241231.xsd#shc_PercentOfRevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9819bc7c-cd27-41fb-93ed-bd10820e030a" xlink:to="loc_shc_PercentOfRevenueFromContractWithCustomerExcludingAssessedTax_c53f7fa1-2816-4822-bc03-76d8c44ad461" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/SegmentandGeographicInformationScheduleofLongLivedAssetsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#SegmentandGeographicInformationScheduleofLongLivedAssetsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/SegmentandGeographicInformationScheduleofLongLivedAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_2bf3a0f1-e3ba-4527-b4d5-0c001a46e160" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_0bf99069-1644-4a0a-b8e9-c80fa986a4bb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2bf3a0f1-e3ba-4527-b4d5-0c001a46e160" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_0bf99069-1644-4a0a-b8e9-c80fa986a4bb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_7aa74b26-d327-4eb8-afc9-2057e448bc4a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_0bf99069-1644-4a0a-b8e9-c80fa986a4bb" xlink:to="loc_srt_StatementGeographicalAxis_7aa74b26-d327-4eb8-afc9-2057e448bc4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_7aa74b26-d327-4eb8-afc9-2057e448bc4a_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_7aa74b26-d327-4eb8-afc9-2057e448bc4a" xlink:to="loc_srt_SegmentGeographicalDomain_7aa74b26-d327-4eb8-afc9-2057e448bc4a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_5cd0b4e7-a150-4e8b-b060-254979cb542d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_7aa74b26-d327-4eb8-afc9-2057e448bc4a" xlink:to="loc_srt_SegmentGeographicalDomain_5cd0b4e7-a150-4e8b-b060-254979cb542d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_1238ab5c-90b1-4ef2-b8a2-4b153b4e129a" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5cd0b4e7-a150-4e8b-b060-254979cb542d" xlink:to="loc_country_US_1238ab5c-90b1-4ef2-b8a2-4b153b4e129a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EuropeMember_2d5b0137-42a4-4aca-9f2d-3c0f0cf73e12" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_EuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5cd0b4e7-a150-4e8b-b060-254979cb542d" xlink:to="loc_srt_EuropeMember_2d5b0137-42a4-4aca-9f2d-3c0f0cf73e12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_225ea9e3-095b-4a21-af94-773ece3c3238" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5cd0b4e7-a150-4e8b-b060-254979cb542d" xlink:to="loc_country_CA_225ea9e3-095b-4a21-af94-773ece3c3238" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_OtherGeographicalAreasMember_6724609b-80ab-4ffc-b23e-bea9048288ff" xlink:href="shc-20241231.xsd#shc_OtherGeographicalAreasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5cd0b4e7-a150-4e8b-b060-254979cb542d" xlink:to="loc_shc_OtherGeographicalAreasMember_6724609b-80ab-4ffc-b23e-bea9048288ff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaMember_1b4daff8-9676-46dc-82af-8dbf5d69a4ea" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_AsiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5cd0b4e7-a150-4e8b-b060-254979cb542d" xlink:to="loc_srt_AsiaMember_1b4daff8-9676-46dc-82af-8dbf5d69a4ea" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LatinAmericaMember_720add23-5300-42e6-854c-aee37a2ae0f7" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LatinAmericaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5cd0b4e7-a150-4e8b-b060-254979cb542d" xlink:to="loc_srt_LatinAmericaMember_720add23-5300-42e6-854c-aee37a2ae0f7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_875a425a-9bdf-4585-9b40-d2b1ddaf51c1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2bf3a0f1-e3ba-4527-b4d5-0c001a46e160" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_875a425a-9bdf-4585-9b40-d2b1ddaf51c1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_shc_PercentOfPropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_28bc41b3-000e-40c7-aa7c-7167222c4cb8" xlink:href="shc-20241231.xsd#shc_PercentOfPropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2bf3a0f1-e3ba-4527-b4d5-0c001a46e160" xlink:to="loc_shc_PercentOfPropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_28bc41b3-000e-40c7-aa7c-7167222c4cb8" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://soterahealth.com/role/ScheduleIIValuationandQualifyingAccountsDetails" xlink:type="simple" xlink:href="shc-20241231.xsd#ScheduleIIValuationandQualifyingAccountsDetails"/>
  <link:definitionLink xlink:role="http://soterahealth.com/role/ScheduleIIValuationandQualifyingAccountsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_c44bbaf7-2717-48e7-8e97-780ce96aac0a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ValuationAndQualifyingAccountsDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_43651726-59c9-48eb-b7a4-ddc5600f3667" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ValuationAndQualifyingAccountsDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_c44bbaf7-2717-48e7-8e97-780ce96aac0a" xlink:to="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_43651726-59c9-48eb-b7a4-ddc5600f3667" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_b418dd82-04e8-4b14-b306-3009f3886df9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_43651726-59c9-48eb-b7a4-ddc5600f3667" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_b418dd82-04e8-4b14-b306-3009f3886df9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_b418dd82-04e8-4b14-b306-3009f3886df9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_b418dd82-04e8-4b14-b306-3009f3886df9" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_b418dd82-04e8-4b14-b306-3009f3886df9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_ba3594dc-f13d-4807-bce5-245b077f2322" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_b418dd82-04e8-4b14-b306-3009f3886df9" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_ba3594dc-f13d-4807-bce5-245b077f2322" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForCreditLossMember_0a6fc00e-67b8-40bf-98d3-a50b048410f4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllowanceForCreditLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_ba3594dc-f13d-4807-bce5-245b077f2322" xlink:to="loc_us-gaap_AllowanceForCreditLossMember_0a6fc00e-67b8-40bf-98d3-a50b048410f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_ceef4b2e-fffa-4324-98e0-bc82901abeaf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_ba3594dc-f13d-4807-bce5-245b077f2322" xlink:to="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_ceef4b2e-fffa-4324-98e0-bc82901abeaf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_a5922907-5630-4b0b-a808-1e0045b803ec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_c44bbaf7-2717-48e7-8e97-780ce96aac0a" xlink:to="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_a5922907-5630-4b0b-a808-1e0045b803ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_19c9b874-3ed4-44bd-b549-098631826828" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_a5922907-5630-4b0b-a808-1e0045b803ec" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_19c9b874-3ed4-44bd-b549-098631826828" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_0b1d7134-673d-47dc-b0be-16d26229871d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_a5922907-5630-4b0b-a808-1e0045b803ec" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_0b1d7134-673d-47dc-b0be-16d26229871d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDeductions_e069d673-e237-44f4-b466-1529f3e9ab6f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationAllowancesAndReservesDeductions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_a5922907-5630-4b0b-a808-1e0045b803ec" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDeductions_e069d673-e237-44f4-b466-1529f3e9ab6f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesAdjustments_7d3a1360-eb2f-4821-938d-8007cc6eb78e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationAllowancesAndReservesAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_a5922907-5630-4b0b-a808-1e0045b803ec" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesAdjustments_7d3a1360-eb2f-4821-938d-8007cc6eb78e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_33c0521c-ae3f-4ac1-8a2a-63448af1a14d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
  </link:definitionLink>
</link:linkbase>
