STIMULUS, noun [Latin This word may be formed on the root of stem, a shoot.] Literally, a goad; hence, something that rouses from languor; that which excites or increases action in the animal system, as a stimulus in medicine; or that which rouses the mind or spirits; as, the hope of gain is a powerful stimulus to labor and action.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI