Definition from Wiktionary, the free dictionary
From Latin rancidus (“stinking, rank, rancid, offensive”), from ranceō (“to stink”) (sense in Middle Latin), from whence also English rancor, in Latin used only in present participle rancens (“stinking”).
- Being rank in taste or smell.
- The house was deserted, with a rancid half-eaten meal still on the dinner table.
- His remarks were rancid; everyone got up and left.
Usage notes 
- Nouns to which "rancid" often gets applied: food, butter, meat, milk, fat, oil, smell, odor, taste.
being rank in taste or smell
rancid — see offensive
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