Rotten
Part of speech: adjective
Definition: Rancid, of perishable items that have been overridden with bacteria and other infectious agents. Cruel or mean.
Example sentence: I'm often accused of saying some pretty rotten things about my mother-in-law. But quite honestly, she's only got one major fault - it's called breathing.
Putrescent
Part of speech: adjective
Definition: becoming putrid; putrefying