Meaning

noun any broad thin and limber covering attached at one edge; hangs loose or projects freely

noun an excited state of agitation

noun the motion made by flapping up and down

originFrom Middle English flap, flappe (“a slap; blow; buffet; fly-flap; something flexible or loose; flap”), related to Saterland Frisian 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 3.0