Decedent's rhymes with:
decedents, decedents, antecedents, decedents, antecedents, decedents, accident's, accidents, antecedents, antioxidants, attendant's, attendants, attendants', correspondents, correspondents', decadents, decedents, defendant's, defendants, defendants', dependents, descendants, descendents, dissidents, dissidents', incidents, independents, nonresidents, oxidants, precedents, president's, presidents', resident's, residents, residents', respondents, respondents', rodents, student's, students, students', superintendent's, superintendents, vice-presidents
Decedent's sounds like:
decadents, decedents, dissidents, dissidents'