Definitions for: Rancid

[adj] smelling of fermentation or staleness
[adj] used of decomposing oils or fats; "rancid butter"; "rancid bacon"

Webster (1913) Definition: Ran"cid, a. [L. rancidus, fr. rancere to be rancid or
rank.]
Having a rank smell or taste, from chemical change or
decomposition; musty; as, rancid oil or butter.

Synonyms: malodorous, sour, stale