near miss

1. A narrowly avoided collision involving two or more aircraft, ships, boats, or motor vehicles.
2. A missile strike that is extremely close to but not directly on target.
3. Something that fails by a very narrow margin: Her campaign for the Senate was a near miss.

[Blend of NEAR THING and MISS¹.]

A narrowly avoided mishap; also, an attempt that falls just short of success. For example, It was a near miss for that truck, since the driver had crossed the center strip into on-coming traffic, or Her horse kept having a near miss in every race, so she decided to sell it. This expression originated during World War II, when it signified a bomb exploding in the water near enough to a ship to damage its hull. Soon afterward it acquired its present meanings.

Any circumstance in flight where the degree of separation between two aircraft is considered by either pilot to have constituted a hazardous situation involving potential risk of collision.

See the Introduction, Abbreviations and Pronunciation for further details.

The noun has one meaning:

Meaning #1: an accidental collision that is narrowly avoided