a drug that is taken for nonmedicinal reasons (usually for mind-altering effects); drug abuse can lead to physical and mental damage and (with some substances) dependence and addiction

(medicine) something that treats or prevents or alleviates the symptoms of disease

tending to soothe or tranquilize

a colorless crystalline drug used as a sedative; irritates the stomach and can be addictive

sedative (trade name Doriden) used to treat some sleep disorders

a sedative that depresses activity of the central nervous system and reduces anxiety and induces sleep