any of a group of drugs, such as heroin, morphine, and pethidine, that produce numbness and stupor. They are used medicinally to relieve pain but are sometimes also taken for their pleasant effects; prolonged use may cause addiction

anything that relieves pain or induces sleep, mental numbness, etc

any illegal drug

of, relating to, or designating narcotics

of or relating to narcotics addicts or users

of or relating to narcosis