Pronunciation: (mō-men'tum), [key]
—pl. -taPronunciation: (-tu), [key] -tums.
1. force or speed of movement; impetus, as of a physical object or course of events: The car gained momentum going downhill. Her career lost momentum after two unsuccessful films.
2. Mech.a quantity expressing the motion of a body or system, equal to the product of the mass of a body and its velocity, and for a system equal to the vector sum of the products of mass and velocity of each particle in the system.
3. Philos.moment (def. 7).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.