flap

American  

[flap] / flæp /

verb (used without object)

flapped, flapping

1. to swing or sway back and forth loosely, especially 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, especially under stress.

   a seasoned diplomat who doesn't flap easily.

---

verb (used with object)

flapped, flapping

1. to move (wings, arms, etc.) up and down.

2. to cause to swing or sway loosely, especially 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.

noun

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.

   1. a state of nervous excitement, commotion, or disorganization.

   2. an emergency situation.

   3. scandal; trouble.

8. Surgery. a portion of skin or flesh that is partially separated from the body and may subsequently be transposed by grafting.

9. Aeronautics. a movable surface used for increasing the lift or drag of an airplane.

10. Phonetics.

    1. 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.

    2. a trill.

    3. 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.

    1. Also called backflap hinge.  Also called flap hinge.  a hinge having a strap or plate for screwing to the face of a door, shutter, or the like.

    2. one leaf of a hinge.

flap British  

/ flæp /

verb

1. to move (wings or arms) up and down, esp in or as if in flying, or (of wings or arms) to move in this way

2. to move or cause to move noisily back and forth or up and down

   the curtains flapped in the breeze

3. informal (intr) to become agitated or flustered; panic

4. to deal (a person or thing) a blow with a broad flexible object

5. to toss, fling, slam, etc, abruptly or noisily

6. (tr) phonetics to pronounce (an (r) sound) by allowing the tongue to give a single light tap against the alveolar ridge or uvula

---

noun

1. the action, motion, or noise made by flapping

   with one flap of its wings the bird was off

2. a piece of material, etc, attached at one edge and usually used to cover an opening, as on a tent, envelope, or pocket

3. a blow dealt with a flat object; slap

4. a movable surface fixed to the trailing edge of an aircraft wing that increases lift during takeoff and drag during landing

5. surgery a piece of tissue partially connected to the body, either following an amputation or to be used as a graft

6. informal a state of panic, distress, or agitation

7. phonetics an (r) produced by allowing the tongue to give a single light tap against the alveolar ridge or uvula

Other Word Forms

• flapless adjective
• unflapping adjective

Etymology

Origin of flap

First recorded in 1275–1325; Middle English flappe “a blow, slap,” flappen “to hit, slap”; compare Dutch flap, flappen

Explanation

You're probably familiar with the verb to "flap," which is what birds do with their wings. But as a noun, a flap is a fuss, an argument, or a gossipy feud. A big part of the pleasure of reality TV shows is watching how quickly a person can start a flap. A dumb remark, a furtive glance, a missed phone call: any of these things can start the characters bickering. And the flap can go on for an entire season! One way to remember the meaning of the verb to flap is to imagine the sound of many wings flapping. That's the sound a flap might make if you could hear it. The leak from the senator's press agent might have caused a firestorm. Instead it resulted in just a minor flap.

Example Sentences

The flap concerns the analysis we told you about last week by four economists at the Federal Reserve Bank of New York.

From The Wall Street Journal • Feb. 19, 2026

"Therefore, getting a cat flap is proving a little bit difficult."

From Barron's • Feb. 15, 2026

Ear cropping , which involves removing all or part of a dog's ear flap, is illegal in the UK.

From BBC • Dec. 6, 2025

Instead, it uses a modified version of Cas9 that cuts just one of the complementary strands, opening up a flap where a new sequence can be inserted.

From Science Daily • Oct. 10, 2025

I zip open the flap, but before I can take a step inside, movement in the shadows almost gives me a heart attack.

From "King and the Dragonflies" by Kacen Callender

Related Words

• dangle
• flail
• flop
• hang
• thrash
• vibrate