Substances or things that increase activity or energy in the body or mind; drugs that speed up the nervous system.
From Latin 'stimulare' (to urge, goad, prick), from 'stimulus' (goad, spur). The meaning evolved from literal goading to substances that 'urge on' bodily functions.
Caffeine, nicotine, and amphetamines are all stimulants that work on the same basic principle—they trick your nervous system into thinking it should be more alert—which is why coffee and cocaine are chemically cousins, just with vastly different potencies.
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