Other forms: flaps, flapping, flapped
To flap is to move something wide and flat up and down, the way a bird beats its wings to get off the ground. A pigeon flapping off the pavement in front of a bus. Washing flapping on the line, a flag flapping against its pole, a moth flapping round a lamp at night.
As a noun a flap is a flat piece fixed along one edge that covers an opening: the flap of an envelope, the cat flap in the back door, the tent flap you unzip and fold back. Aircraft wings have flaps that come down for landing and make the whole cabin rumble. There is an informal sense as well, because a flap is a state of fuss and panic, and somebody in a flap has lost the thread completely. Do not mix flap with flip: you flip a pancake, you flap your arms.
1verbflapTo move wings or something flat up and down through the air.
“The swan flapped twice and cleared the water.”
2verblooselyTo move loosely and noisily in the wind.
“The tarpaulin flapped all night and nobody in the house slept.”
3nouncoverA flat piece attached along one edge that covers an opening.
“He licked the flap of the envelope and pressed it down with his thumb.”
4nounpanicA state of panic or fuss.
“There was a flap at the office when the auditors arrived a day early.”
Flap comes from Middle English flap or flappe, which named a slap, a blow, or anything loose and flexible, and the sound of the word is doing half the work. Its neighbours across the North Sea are Middle Dutch flabbe, a slap in the face, and modern Dutch flap. English flab and flabby belong to the same loose, floppy family.
Middle English
flap
English, today
flap
Built from
From Middle English flap, flappe (“a slap; blow; buffet; fly-flap; something flexible or loose; flap”), related to stq Flappert (“wing, flipper”), Middle Dutch flabbe (“a blow; slap on the face; fly-flap; flap”) (modern Dutch flap (“flap”)), Middle Low German flabbe, vlabbe, flebbe, from the verb (see below). Related also to English flab and flabby.
Etymology from Wiktionary, CC BY-SA