S: (n) flap (a movable piece of tissue partly connected to the body)
S: (n) flap, flaps (a movable airfoil that is part of an aircraft wing; used to increase lift or drag)
Verb
S: (v) roll, undulate, flap, wave (move in a wavy pattern or with a rising and falling motion) "The curtains undulated"; "the waves rolled towards the beach"
S: (v) flap (move noisily) "flags flapped in the strong wind"
S: (v) beat, flap (move with a thrashing motion) "The bird flapped its wings"; "The eagle beat its wings and soared high into the sky"
S: (v) beat, flap (move with a flapping motion) "The bird's wings were flapping"