1. a form of locomotion that allows some animals (notably birds, bats, and insects) to become airborne and travel varying distances. It has several forms: active flight, gliding, and hovering. Bones of flying vertebrates must be light and rigid. Flight is used for escaping danger, locating food, and migrating from one location to another as seasons change (see migration).

2. rapid departure as a means of escape from danger, whether by flying or some other form of locomotion. See also fight-or-flight response.