Definition from Wiktionary, the free dictionary
From Persian پادزهر (pâdzahr, “to expel poison”) (In ancient times, bezoars from animals were ground up and ingested as remedies for various maladies and as antidotes to poisons.)
bezoar (plural bezoars)
- (chiefly UK) A mass, usually of hair or undigested vegetable matter, found in an animal's intestines. A hairball.
- An enterolith.
Related terms 
bezoar m (plural bezoares)