Merriam-Webster's Collegiate® Dictionary, 11th Edition TARTAR tartar emetic noun Date: circa 1704 a poisonous efflorescent crystalline salt C 8 H 4 K 2 O 12 Sb 2 {bull}3H 2 O of sweetish metallic taste that is used in dyeing as a mordant and especially formerly in medicine as an emetic and expectorant
