| | | | | | | | | | | | | | | | | | | | | |
<?xml version="1.0" encoding="windows-1252"?> |
<!-- Generated by DFIN XBRL Instance Document - http://www.dfinsolutions.com/ - Version R3.0 - on 19-March-2024 [02:16:57] {PM} --> |
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:xbrldt="http://xbrl.org/2005/xbrldt"> |
| <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#PvpAdjustmentsOnly" roleURI="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly"/> |
| <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/> |
| <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"/> |
| <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"/> |
| <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"/> |
| <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"/> |
| <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll"/> |
| <definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly"> |
| | <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AllAdjToCompMember" xlink:label="AllAdjToCompMember"/> |
| | <loc xlink:type="locator" xlink:href="avtr-20231231.xsd#avtr_ChangeInTheActuarialPresentValueOfPensionBenefitsMember" xlink:label="ChangeInTheActuarialPresentValueOfPensionBenefitsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="AllAdjToCompMember" xlink:to="ChangeInTheActuarialPresentValueOfPensionBenefitsMember" order="100"/> |
| | <loc xlink:type="locator" xlink:href="avtr-20231231.xsd#avtr_ServiceCostOfPensionBenefitsMember" xlink:label="ServiceCostOfPensionBenefitsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="AllAdjToCompMember" xlink:to="ServiceCostOfPensionBenefitsMember" order="101"/> |
| | <loc xlink:type="locator" xlink:href="avtr-20231231.xsd#avtr_YearEndFairValueOfAwardsGrantedInTheCurrentFiscalYearMember" xlink:label="YearEndFairValueOfAwardsGrantedInTheCurrentFiscalYearMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="AllAdjToCompMember" xlink:to="YearEndFairValueOfAwardsGrantedInTheCurrentFiscalYearMember" order="102"/> |
| | <loc xlink:type="locator" xlink:href="avtr-20231231.xsd#avtr_FairValueOfEquityCompensationGrantedInCurrentYearValueAtYearEndMember" xlink:label="FairValueOfEquityCompensationGrantedInCurrentYearValueAtYearEndMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="AllAdjToCompMember" xlink:to="FairValueOfEquityCompensationGrantedInCurrentYearValueAtYearEndMember" order="103"/> |
| | <loc xlink:type="locator" xlink:href="avtr-20231231.xsd#avtr_DividendsAccruedOnUnvestedSharesShareUnitsMember" xlink:label="DividendsAccruedOnUnvestedSharesShareUnitsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="AllAdjToCompMember" xlink:to="DividendsAccruedOnUnvestedSharesShareUnitsMember" order="104"/> |
| | <loc xlink:type="locator" xlink:href="avtr-20231231.xsd#avtr_ChangeInFairValueFromEndOfPriorFiscalYearToEndOfCurrentFiscalYearForAwardsMadeInPriorFiscalYearsThatWereUnvestedAtEndOfCurrentFiscalYearMember" xlink:label="ChangeInFairValueFromEndOfPriorFiscalYearToEndOfCurrentFiscalYearForAwardsMadeInPriorFiscalYearsThatWereUnvestedAtEndOfCurrentFiscalYearMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="AllAdjToCompMember" xlink:to="ChangeInFairValueFromEndOfPriorFiscalYearToEndOfCurrentFiscalYearForAwardsMadeInPriorFiscalYearsThatWereUnvestedAtEndOfCurrentFiscalYearMember" order="105"/> |
| | <loc xlink:type="locator" xlink:href="avtr-20231231.xsd#avtr_ChangeInFairValueFromEndOfPriorFiscalYearToVestingDateForAwardsMadeInPriorFiscalYearsThatVestedDuringCurrentFiscalYearMember" xlink:label="ChangeInFairValueFromEndOfPriorFiscalYearToVestingDateForAwardsMadeInPriorFiscalYearsThatVestedDuringCurrentFiscalYearMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="AllAdjToCompMember" xlink:to="ChangeInFairValueFromEndOfPriorFiscalYearToVestingDateForAwardsMadeInPriorFiscalYearsThatVestedDuringCurrentFiscalYearMember" order="106"/> |
| | <loc xlink:type="locator" xlink:href="avtr-20231231.xsd#avtr_FairValueOfForfeitedAwardsDeterminedAtEndOfPriorYearForAwardsMadeInPriorFiscalYearsThatWereForfeitedDuringCurrentFiscalYearMember" xlink:label="FairValueOfForfeitedAwardsDeterminedAtEndOfPriorYearForAwardsMadeInPriorFiscalYearsThatWereForfeitedDuringCurrentFiscalYearMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="AllAdjToCompMember" xlink:to="FairValueOfForfeitedAwardsDeterminedAtEndOfPriorYearForAwardsMadeInPriorFiscalYearsThatWereForfeitedDuringCurrentFiscalYearMember" order="107"/> |
| | </definitionLink> |
| </linkbase> |