The deepest malignity or spite; deep-seated enmity or malice; inveterate hatred. To stint rancour and dissencioun. It would not be easy to conceive the passion, rancor, and malice of their tongues and hearts. (Burke)
Rancor, enmity. Enmity and rancor both describe hostile feelings; but enmity may be generous and open, while rancor implies personal malice of the worst and most enduring nature, and is the strongest word in our language to express hostile feelings. Rancor will out; proud prelate, in thy face I see thy fury. (Shak) Rancor is that degree of malice which preys upon the possessor. (Cogan)
Origin: OE. Rancour, OF. Rancor, rancur, F. Rancune, fr. L. Rancor rancidity, rankness; tropically, an old grudge, rancor, fr. Rancere to be rank or rancid.