v. & n.
v. (flapped, flapping) 1 a tr. move (wings, the arms, etc.) up and down when flying, or as if flying. b intr. (of wings, the arms, etc.) move up and down; beat. 2 intr. colloq. be agitated or panicky. 3 intr. (esp. of curtains, loose cloth, etc.) swing or sway about; flutter. 4 tr. (usu. foll. by away, off) strike (flies etc.) with something broad; drive. 5 intr. colloq. (of ears) listen intently.
n. 1 a piece of cloth, wood, paper, etc. hinged or attached by one side only and often used to cover a gap, e.g. a pocket-cover, the folded part of an envelope, a table-leaf. 2 one up-and-down motion of a wing, an arm, etc. 3 colloq. a state of agitation; panic (don't get into a flap). 4 a hinged or sliding section of a wing used to control lift; an aileron. 5 a light blow with something broad. 6 an open mushroom-top. flappy adj.
[ ME, prob. imit. ]