[im.pe.tus] n [L, assault, impetus, fr. impetere to attack, fr. in- + petere to go to, seek--more at feather] (1641) 1 a (1): a driving force: impulse (2): incentive, stimulus b: stimulation or encouragement resulting in increased activity
2: the property possessed by a moving body in virtue of its mass and its motion--used of bodies moving suddenly or violently to indicate the origin and intensity of the motion