impetusn.[L., fr. impetere to rush upon, attack; pref. im- in + petere to fall upon, seek. See Petition.]1. A property possessed by a moving body in virtue of its weight and its motion; the force with which any body is driven or impelled; momentum.()()2. Fig.: Impulse; incentive; stimulus; vigor; force; as, the President's strong recommendation provided the impetus needed to pass the campaign reform bill.(Buckle.)3. (Gun.) The altitude through which a heavy body must fall to acquire a velocity equal to that with which a ball is discharged from a piece.()()