ran·cor 
(răngkər)
(răngkər)n.
Bitter, long-lasting resentment; deep-seated ill will: He was filled with rancor after losing his job.
[Middle English, from Old French, from Late Latin, rancid smell, from Latin rancēre, to stink, be rotten.]
rancor·ous adj.
rancor·ous·ly adv.
rancor·ous·ness n.