S: (n) drug of abuse, street drug (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)
S: (n) amphetamine, pep pill, upper, speed (a central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression)
S: (n) gateway drug (a habit-forming drug that is not addictive but its use may lead to the use of other addictive drugs) "one college athlete recently called beer a gateway drug for young people"