Flop  —v. (-pp-) 1 sway about heavily or loosely. 2 (often foll. By down, on, into) fall or sit etc. Awkwardly or suddenly. 3 slang fail; collapse (play flopped). 4 make a dull soft thud or splash. —n. 1 flopping movement or sound. 2 slang failure. —adv. With a flop. [var. Of *flap]