a white, crystalline derivative of morphine, CHNO, used, usually in the form of its hydrochloride, to counteract the effects of narcotic overdoses and to aid in diagnosing narcotic addiction
See nalorphine in American Heritage Dictionary 4
(nălˈər-fēnˌ, năl-ôrˈfēn)
noun
A drug, C19H21NO3, derived from morphine, used to treat respiratory depression and other effects of an overdose of narcotics.