<p><strong>Verb (used without object)</strong></p><ul><li>flapped, flap·ping: to swing or sway back and forth loosely, especially with noise: A loose shutter flapped outside the window.</li><li>to move up and down, as wings; flap the wings, or make similar movements.</li><li>to strike a blow with something broad and flexible.</li><li>Slang: to become excited or confused, especially under stress: a seasoned diplomat who doesn't flap easily.</li></ul><p><strong>Verb (used with object)</strong></p><ul><li>flapped: to move (wings, arms, etc.) up and down.</li><li>to cause to swing or sway loosely, especially with noise.</li><li>to strike with something broad and flat.</li><li>to toss, fold, shut, etc., smartly, roughly, or noisily.</li></ul><p><strong>Noun</strong></p><ul><li>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.</li><li>either of the two segments of a book jacket folding under the book's front and back covers.</li><li>one leaf of a folding door, shutter, or the like.</li><li>a flapping motion.</li><li>the noise produced by something that flaps.</li><li>a blow given with something broad and flat.</li><li>Slang: a state of nervous excitement, commotion, or disorganization.</li><li>an emergency situation.</li><li>scandal; trouble.</li><li>Surgery: a portion of skin or flesh that is partially separated from the body and may subsequently be transposed by grafting.</li><li>Aeronautics: a movable surface used for increasing the lift or drag of an airplane.</li><li>Phonetics: 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.</li><li>a trill.</li><li>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.</li><li>Building Trades: Also called back-flap hinge, a hinge having a strap or plate for screwing to the face of a door, shutter, or the like.</li><li>one leaf of a hinge.</li></ul>