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mid-15c., "to blow away something" (of wind), from Latin ventilatus, past participle of ventilare "to brandish, toss in the air, winnow, fan, agitate, set in motion," from ventulus "a breeze," diminutive of ventus "wind" (see wind (n.1)). Original notion is of cleaning grain by tossing it in the air and letting the wind blow away the chaff. Meaning "supply a room with fresh air" first recorded 1660s (implied in ventilation). Slang sense of "shoot" (someone) is recorded from 1875. Related: Ventilated; ventilating.