—v.i. 1. to swing or sway back and forth loosely, esp. with noise: A loose shutter flapped outside the window. 2. to move up and down, as wings; flap the wings, or make similar movements.
3. to strike a blow with something broad and flexible.
4. Slang.to become excited or confused, esp. under stress: a seasoned diplomat who doesn't flap easily.
—v.t. 1. to move (wings, arms, etc.) up and down.
2. to cause to swing or sway loosely, esp. with noise.
3. to strike with something broad and flat.
4. to toss, fold, shut, etc., smartly, roughly, or noisily.
5. Phonetics.to pronounce (a sound) with articulation resembling that of a flap: The British often flap their r's.
—n. 1. something flat and broad that is attached at one side only and hangs loosely or covers an opening: the flap of an envelope; the flap of a pocket. 2. either of the two segments of a book jacket folding under the book's front and back covers.
3. one leaf of a folding door, shutter, or the like.
4. a flapping motion.
5. the noise produced by something that flaps.
6. a blow given with something broad and flat.
7. Slang. a. a state of nervous excitement, commotion, or disorganization.
b. an emergency situation.
c. scandal; trouble.
8. Surg.a portion of skin or flesh that is partially separated from the body and may subsequently be transposed by grafting.
9. Aeron.a movable surface used for increasing the lift or drag of an airplane.
10. Phonet. a. a rapid flip of the tongue tip against the upper teeth or alveolar ridge, as in the r-sound in a common British pronunciation of very, or the t-sound in the common American pronunciation of water. b. a trill.
c. a flipping out of the lower lip from a position of pressure against the upper teeth so as to produce an audible pop, as in emphatic utterances containing f-sounds or v-sounds.
11. Building Trades. a. Also calledbackflap hinge,flap' hinge". a hinge having a strap or plate for screwing to the face of a door, shutter, or the like. See illus. under hinge. b. one leaf of a hinge.