[noun] a movable piece of tissue partly connected to the body
[noun] a movable airfoil that is part of an aircraft wing; used to increase lift or drag
[verb] move in a wavy pattern or with a rising and falling motion; "The curtains undulated"; "the waves rolled towards the beach" Synonyms:roll, undulate, wave
[verb] move noisily; "flags flapped in the strong wind"
[verb] move with a thrashing motion; "The bird flapped its wings"; "The eagle beat its wings and soared high into the sky" Synonyms:beat
[verb] move with a flapping motion; "The bird's wings were flapping" Synonyms:beat
[verb] make a fuss; be agitated Synonyms:dither, pother