1640s, from Latin rancidus "rank, stinking, offensive" (also source of Italian rancido, Spanish rancio), from rancere "be spoiled or rotten," of unknown origin. German ranzig is fr [..]

unhygienic, stale, or having a bad taste or smell.

An unpleasant taste in the coffee brew caused by the oxidation of the fats.

The breakdown of the polyunsaturated fatty acids in fats that results in disagreeable odors and flavors.

A term describing fatty foods or the fat itself which has gone stale due to oxidation of the fat. This is accelerated by exposure to light, high temperatures, or prolonged contact with a metallic subs [..]

(adj) (used of decomposing oils or fats) having a rank smell or taste usually due to a chemical change or decomposition(adj) smelling of fermentation or staleness

  Having a disagreeable odour and taste.

A stale, unpleasant aroma or flavor, often produced by oxidized or decomposed oils. Example: Old potato chips and spoiled salad dressing can have rancid aromas and flavors.

Rancid: A tasting term to describe a product with a fetid or tainted character.

Having a smell or taste of stale fats or oils.

Having the bad smell or taste of spoiled (oxidized) fats or oils; nuts may also be rancid; rancid fats are a carcinogen and should not be consumed.

Being rank in taste or smell. ''The house was deserted, with a rancid half-eaten meal still on the dinner table.'' offensive ''His remarks were rancid; everyone got up and left.''