Superstitious
discreditable
abhorring
standardizing
atheism
There isn't one. A baker's dozen is thirteen items.
13 = thirteen.
A thirteen letter word that ends with tending: overextending
What is a thirteen letter word for the French and Indian Revolution?
The letter "i" in "thirteen" is not silent.
stabilization
appropriately
discreditable
abhorring
abbreviationsabnormalitiesabolitionistsaccelerationsacceptabilityaccommodationaccompanimentaccomplishingaccreditationaccumulationsacknowledgingacquaintancesacrobaticallyadjustabilityadministratoradmissibilityadvertisementaffirmativelyaffordabilityalgebraicallyalliterationsamortizationsanniversariesannouncementsapplicabilityapportionmentapproximatelyarchitecturalargumentativeassassinationattainabilityauthorizationautobiography
conflagration
actualizationapproximationconfigurationconstellationconsolidationcontaminationcontributionscommunicationdisconcertingdisconnectingdistributionsincriminationinvestigationinstitutionalinformationalintellectualsmanifestationnonnegotiablenonreturnableprotectionismperfectionismprivatizationproliferationreorganizationreproductionsrevolutionarysubordinationunintentionalunconditional
standardizing