he most helpful way to remember rancor with all its dark, miserable bitterness is to think of how rancor rhymes with canker, as in canker sore, the horrible painful burning on your lip. Or, you might want to remind yourself that rancor has its roots in the word rancid meaning "rotten." Rancor refers particularly to the sort of ill-will associated with resentment, envy, slow-brewing anger, and a very personal sort of hatred.