narcotic

Universal Words noun, adjective noun 1 a powerful illegal drug that affects the mind in a harmful way. HEROIN and COCAINE are narcotics: a narcotics agent (= a police officer investigating the illegal trade in drugs) 2 (medical) a substance that relaxes you, reduces pain or makes you sleep: a mild narcotic adjective 1 (of a drug) that affects your mind in a harmful way 2 (of a substance) making you sleep: a mild narcotic effect