flap (flaps plural & 3rd person present) (flapping present participle) (flapped past tense & past participle )
1 verb If something such as a piece of cloth or paper flaps or if you flap it, it moves quickly up and down or from side to side.
(=flutter)
Grey sheets flapped on the clothes line... V
2 verb If a bird or insect flaps its wings or if its wings flap, the wings move quickly up and down.
The bird flapped its wings furiously... V pl-n
3 verb If you flap your arms, you move them quickly up and down as if they were the wings of a bird.
...a kid running and flapping her arms. V n
4 n-count A flap of cloth or skin, for example, is a flat piece of it that can move freely up and down or from side to side because it is held or attached by only one edge.
He drew back the tent flap and strode out into the blizzard.
5 n-count A flap on the wing of an aircraft is an area along the edge of the wing that can be raised or lowered to control the movement of the aircraft.
...the sudden slowing as the flaps were lowered.