Definition of: momentum

(mō·men′təm) noun plural ·ta (-tə) or ·tums
1. Mech. The impetus of a moving body.
2. Physics The quantity of motion in a body as measured by the product of its mass and velocity.
3. An essential or constituent element.
4. Music An eighth rest. [<L. Doublet of MOMENT.]
—mo·men′tal adjective