A technique performed by skilled players of Super Smash Bros. Melee. To execute a wavedash, one must make a very short jump into the air, and then move diagonally downward while dodging in midair with the L button. One wavedash by itself is not particularly useful; it is when the move is repeated rapidly that it becomes both impressive and practical.
Wavedashing is most useful for quickly escaping from close combat with an opponent. Also, it can get you from one end of a stage to the other faster than running or jumping. In some instances, it can also be used as a type of taunt, a means of rubbing your skill in an opponent's face.
Any time you are fighting against an opponent who knows how to do the wavedash, chances are good that that person possesses above-average Smash skills.
Ben couldn't land a single hit on Josh because Josh was wavedashing all over the stage.
Wavedashing is an advanced technique in Super Smash Bros. Melee that is generally frowned upon by many players, considered an unfair advantage, like Mario Karts' snaking, to do it you press X or Y, then L or R, then diagonal down on the analog stick.
Steve:Ha! I win!
Bob:Bitch, you just kept wavedashing.