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1. An act of colliding; a crash.
2. A condition of opposition or conflict between two or more people or things: the collision between management and labor.
3. Physics A brief dynamic event consisting of the close approach of two or more particles, such as atoms, resulting in an abrupt change of momentum or exchange of energy.

[Middle English, from Late Latin collīsiō, collīsiōn-, from Latin collīsus, past participle of collīdere, to collide; see collide.]

col·li′sion·al adj.
col·li′sion·al·ly adv.
Synonyms: collision, crash1, impact
These nouns denote violent forcible contact between two or more things: the midair collision of two planes; a crash involving two cars; a crater produced by the comet's impact.


in the manner of a collision or collisions
References in periodicals archive ?
We will extend our dust and gas emission modelling code to include dust heating not just by radiation but also by particle impacts, in order to determine accurate dust masses for collisionally ionized supernova remnants covered by Herschel surveys of the Magellanic Clouds and Milky Way.
Frantzeskakis, "Matter-wave solitons of collisionally inhomogeneous condensates," Physical Review A, vol.
Source conditions were as follows: Curtain Gas, 40; gas 1, 35; gas 2, 30; temperature, 600; collisionally activated dissociation gas, 12; ion spray voltage, 5500; and entrance potential, 10.