rancid (adj.)youdaoicibaDictYouDict
1640s, from Latin rancidus "rank, stinking, offensive" (also source of Italian rancido, Spanish rancio), from rancere "be spoiled or rotten," of unknown origin. German ranzig is from French rancide. Related: Rancidness.
rancor (n.)youdaoicibaDictYouDict
c. 1200, from Old French rancor "bitterness, resentment; grief, affliction," from Late Latin rancorem (nominative rancor) "rancidness, a stinking smell" (Palladius); "grudge, bitterness" (Hieronymus and in Late Latin), from Latin rancere "to stink" (see rancid).