\Im"pe*tus\, n. [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.
Note: Momentum is the technical term, impetus its popular
      equivalent, yet differing from it as applied commonly
      to bodies moving or moved suddenly or violently, and
      indicating the origin and intensity of the motion,
      rather than its quantity or effectiveness.
2. Fig.: Impulse; incentive; vigor; force. --Buckle.
3. (Gun.) The aititude through which a heavy body must fall
   to acquire a velocity equal to that with which a ball is
   discharged from a piece.