rancor

rancor \RANG-ker\, noun:

bitter resentment or ill will; extreme hatred or spite

The day quickly degenerated into rancor as Palestinians and Jews staged competing protests and Arab participants were accused of harassing Jewish delegates.
-- Rachel L. Swarns, New York Times, 2001-08-31

He called for unity after years of partisan rancor and division.
-- Alec MacGillis, The Sydney Morning Herald, 2008-01-22

c 1225, from Old French rancor, from Latin rancorem "rancidness, grudge, bitterness," from Latin rancere "to stink."