flap
1. flap \'flap\ n [ME flappe] 1: a stroke with something broad : SLAP obs 2: something broad and flat used for striking 3: something that is broad, limber, or flat and usu. thin and that hangs lo ose or projects freely : as 3a: a piece on a garment that hangs free 3b: a piece of tissue partly severed from its place of origin for use in su rgical grafting 3c: an extended part forming the closure (as of an envelope) 3d: a movable auxiliary airfoil usu. attached to an airplane wing's trailin g edge 4: the motion of something broad and limber 2. flap vb or flapped; or flap.ping 1: to beat with or as if with a flap 2: to toss sharply : FLING 3: to move or cause to move in flaps 1: to sway loosely usu. with a noise of striking and esp. when moved by wi nd 2a: to beat or pulsate wings or something suggesting wings 2b: to progress by flapping 3: to flutter ineffectively
Webster's English Dictionary