Pronunciation: (ku-lizh'un), [key]
1. the act of colliding; a coming violently into contact; crash: the collision of two airplanes.
2. a clash; conflict: a collision of purposes.
3. Physics.the meeting of particles or of bodies in which each exerts a force upon the other, causing the exchange of energy or momentum.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.