stimulation n.

plural stimuli, 1680s, originally as a medical term, "something that goads a lazy organ" (often the male member), from a modern use of Latin stimulus "a goad, a pointed stick," figuratively "a sting, a pang; incitement, spur," from PIE *sti- "point, prick, pierce" (see stick (v.)). General sense of "something that excites or arouses the mind or spirit" is from 1791. Psychological sense is first recorded 1894.

1772, from French stimulant or directly from Latin stimulantem (nominative stimulans), present participle of stimulare "to prick, urge, stimulate" (see stimulation). As a noun from 1794.

1610s, "rouse to action," from Latin stimulatus, past participle of stimulare (see stimulation). Related: Stimulated; stimulating.