Narcotic

Part of speech: noun (n.)

A drug which, in medicinal doses, generally allays morbid susceptibility, relieves pain, and produces sleep; but which, in poisonous doses, produces stupor, coma, or convulsions, and, when given in sufficient quantity, causes death. The best examples are opium (with morphine), belladonna (with atropine), and conium. Nercotykes and opye (opium) of Thebes. Chaucer.

Part of speech: adjective (a.)

Having the properties of a narcotic; operating as a narcotic. -- Nar*cot"ic*ness, n.