News stories frequently cover accidents where a car hits a bus, a train hits a car, a bicycle hits a pedestrian, and so forth. These are frequently called “collisions.”
In newspaper parlance, a “collision” occurs only when both objects are in motion. The Associated Press Stylebook says: “Two objects must be in motion before they can collide. A moving train cannot collide with a stopped train.” The New York Times Manual of Style and Usage advises: “Only two objects in motion can collide. If the phrase collided with seems to fix blame, avoid it by using this construction: a truck and a bus collided.”
So, according to that prohibition, when a fourth-grader comes up against the playground wall hard enough to cause him to wail, he cannot “collide” with it; he can only “hit” it, “run into” it, or otherwise strike it.
The problem with this is the loss of a good vivid image, and for no reason discernible through etymology or usage outside of the news business.
Dictionary definitions of “collide” have no requirement for the number of objects that must be in motion. Webster’s New World College Dictionary, the choice of many news organizations, says merely that “collide” means “to come into violent contact; strike violently against each other; crash” or “to come into conflict; clash.” The objects merely need to come together with force.
Merriam-Webster’s Dictionary of English Usage believes that a string of newspaper editors beginning with William Cullen Bryant in 1877 may have foisted this usage on an unsuspecting readership.
The very notion that two passenger conveyances could “collide” was considered insulting by the British, according to the Oxford English Dictionary, which said: “When first used of railway trains or ships in collision, c1860-70, it was much objected to as an Americanism.” It is pure conjecture that Bryant or someone like him decided to address that distaste by making sure it applied only to specific conditions, i.e. both ships or trains moving at the time.
Nonetheless, things “collide” all the time without both of them being in motion, and sometimes without any of them actually moving. When two ideologies “collide,” for example, nothing moves physically; it’s simply a clash of ideas. And the only difference between a “collision” of two cars that are moving and a “collision” when one of the cars is stopped at a stop sign is in the charges that might result. It’s still a forceful event.