noun, plural im·pe·tus·es.
- a moving force; impulse; stimulus: The grant for building the opera house gave impetus to the city’s cultural life.
- (broadly) the momentum of a moving body, especially with reference to the cause of motion.
noun plural -tuses
- an impelling movement or force; incentive or impulse; stimulus
- physics the force that sets a body in motion or that tends to resist changes in a body’s motion
early 15c., impetous “rapid movement, rush;” 1640s, with modern spelling, “force with which a body moves, driving force,” from Latin impetus “attack, assault, onset, impulse, violence, vigor, force, passion,” related to impetere “to attack,” from assimilated form of in- “into, in, on, upon” (see in- (2)) + petere “aim for, rush at” (see petition (n.)).