rancid

UK: /ˈrænsɪd/ US: /ˈrænsɪd/ ,(ran′sid)

WordReference Random House Learner's Dictionary of American English © 2025

ran•cid /ˈrænsɪd/   adj. 

1. having an unpleasant smell or taste, usually because of decay:
   rancid butter.

ran•cid•i•ty/rænˈsɪdɪti/  ran•cid•ness, n. [uncountable]

WordReference Random House Unabridged Dictionary of American English © 2025

ran•cid  (ran′sid), adj. 

1. having a rank, unpleasant, stale smell or taste, as through decomposition, esp. of fats or oils:
   rancid butter.
2. (of an odor or taste) rank, unpleasant, and stale:
   a rancid smell.
3. offensive or nasty;
   disagreeable.

• Latin rancidus rank, stinking, equivalent. to ranc(ēre) to be rotten + -idus -id⁴
• 1640–50

ran′cid•ly, adv. 
ran′cid•ness, ran•cid′i•ty, n. 

Collins Concise English Dictionary © HarperCollins Publishers::

rancid / ˈrænsɪd/ adjective

1. (of butter, bacon, etc) having an unpleasant stale taste or smell as the result of decomposition
2. (of a taste or smell) rank or sour; stale

Etymology: 17th Century: from Latin rancidus rank, from rancēre to stink

rancidity / rænˈsɪdɪtɪ/, ˈrancidness noun