Definition of "collision"

collision

/kəˈlɪʒən/

noun
countable and uncountable, plural collisions
1. An instance of colliding.
  Quotations
  At the very moment he cried out, David realised that what he had run into was only the Christmas tree. Disgusted with himself at such cowardice, he spat a needle from his mouth, stepped back from the tree and listened. There were no sounds of any movement upstairs: no shouts, no sleepy grumbles, only a gentle tinkle from the decorations as the tree had recovered from the collision.
  1994, Stephen Fry, chapter 2, in The Hippopotamus
2. (physics) Any event in which two or more bodies exert forces on each other in a relatively short time. In a collision, physical contact of two bodies is not necessary.
3. (software compilation) Clipping of naming collision.
4. (computing, chiefly video games) Clipping of collision detection; tangibility.