= compound containing the fundamental morphine or thebaine structure possessing some affinity to any, or all, of the opioid receptor subtypes Examples are heroin, buprenorphine and naltrexone
a class of codeine-derived, controlled narcotics, such as Tylenol #3, Percocet (oxycodone), Darvon (propoxyphene) and methadone; used to manage severe cases of Restless Legs Syndrome and Periodic Limb Movement Disorder
{i} narcotic drug containing opium; anything which soothes or causes sleepiness or dullness of the senses; pharmaceutical substance which has properties similar to opium and its derivatives
Any substance, natural or synthetic, that is related in action to morphine and binds to the same, or some of the same, receptors Some writers use it just to mean opium, morphine, codeine, and heroin - the natural ingredients of the poppy and their derivatives, excluding the synthetic narcotic analgesics