That flaps. Applied spec. to the upward and downward movement of the wings of birds and, formerly, of flying machines. So flapping flight, etc.

†Striking; †flapping; dialect swooping, pouncing.

Inclined to swing or toss loosely about.

That ‘goes flip-flap’ (see A.).

Flapping. Also figurative: worried, agitated (colloquial). Only in predicative use.

That flaps.