What is the meaning of Flap?

Anything broad and flexible that hangs loose, or that is attached by one side or end and is easily moved.

A hinged leaf.

A hinged surface on the trailing edge of the wings of an aeroplane, used to increase lift and drag.

A side fin of a ray.

The motion of anything broad and loose, or a sound or stroke made with it.

A controversy, scandal, stir, or upset.

A consonant sound made by a single muscle contraction, such as the sound /ɾ/ in the standard American English pronunciation of body.

A piece of tissue incompletely detached from the body, as an intermediate stage of plastic surgery.

The labia, the vulva.

A blow or slap (especially to the face).

A young prostitute.

A connected component of the induced subgraph formed by deleting a set of vertices.

To move (something broad and loose) up and down.

To move loosely back and forth.

To pronounce (something) as a flap consonant.

To be pronounced with a flap consonant.

To be advertised as being available and then unavailable (or available by different routes) in rapid succession.

flap (something flexible that is loose)

banknote

flap

blow, hit

Source: wiktionary.org