collision
Pluralcollisions
- 1An occurrence of two or more things striking or crashing into each other.
The collision crumpled the front of both vehicles.
Investigators examined the collision to determine which driver was at fault.
Similarcrash, impact, smash, pileup, bump
Note
Latin supplies the image directly: collīdere, "to dash together," reached English through Late Latin collīsiō and Middle French collision, and collide is its verb. The noun counts both ways: a collision, two collisions, or collision on its own for the event in general. It need not be grand. In Stephen Fry's The Hippopotamus (1994), what David runs into turns out to be only a Christmas tree.
- 2An event in which two or more bodies exert forces on each other over a relatively short time, without necessarily making physical contact.
Physicists calculate how much energy a collision transfers between particles.
Even a near miss counts as a collision when the two bodies deflect each other.
Similarinteraction, encounter
Note
Here the word drops its everyday picture of impact. What matters is that forces act strongly over a brief interval, not that surfaces touch. Two charged particles that repel each other and fly apart have collided in this sense, exchanging momentum and energy without ever meeting. That is why physicists speak of collisions between bodies that, in the everyday sense, never strike at all.
- 3Short for collision detection.
The level shipped with broken collision, letting players clip into the terrain.
Developers spent days fixing the collision on the staircase model.
Note
In games the word names a property as much as an event. It stands for tangibility itself, the engine's sense of whether shapes are occupying the same space. Broken collision lets a player walk through walls or sink into terrain. The full term, collision detection, also names an Ethernet mechanism for catching two computers sending frames at once, but the clipped form lives chiefly in video games.
- 4Short for naming collision.
Importing both libraries caused a collision between their identically named classes.
The build failed because of a collision in the global namespace.
Note
A programmer's shortening of naming collision. Two variables, functions or other source-code elements end up with the same name, and the build cannot tell them apart. Context supplies the missing word: near "namespace" or "import" the clash is about names, not shapes. Keep it distinct from the game developer's clipping, where the collision is between objects in space.
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Origin
This word came through Middle French collision from Late Latin collīsiō, which goes back to the Latin verb collīdere (past participle collīsus), meaning "to dash together"; it is related to collide.