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: It's a good thing that beauty is only skin deep, or I'd be rotten to the core.
Decayed
Part of speech: verb
Definition: To deteriorate, to get worse, to lose strength or health, to decline in quality.
Part of speech: adjective
Definition: Describing something that has, or is in process, of decaying.