Any drug that excites any bodily function; usually one that stimulates the central nervous system , inducing alertness, elevated mood, wakefulness, increased speech and motor activity, and decreased appetite.
Their mood-elevating effects make some stimulants (e.g., amphetamine s, caffeine and its relatives, cocaine , nicotine ) potent drugs of abuse (see drug addiction ). Ritalin , prescribed for attention deficit disorder in children, is a mild stimulant.