flap /flæp/ I. vi. & vt. (flapped, flapping) （使）拍动，（使）飘动/扬，(鸟翼)振动：red flags flapping in the wind 迎风飘扬的红旗；flap the wings 振翅The wind flapped the sails. 风吹帆飘。［考句］ The wings of the bird still flapped after it had been shot down.鸟被击落后翅膀还在拍打。‖II. n. ［c］片状垂悬物(如信封的口盖、衣服的袋盖等)：stick down the flap of the envelope 粘上信封口盖；the flap of a pocket  (a table) 口袋盖(桌子的活边)