rancorous (adj.)

c. 1200, rancour, "a nourished envy; bitterness, hatred, malice," 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," a word of unknown etymology (compare rancid). Sometimes in 15c. medical works the word is used in English in its literal Latin sense.