Clap1  —v. (-pp-) 1 a strike the palms of one's hands together, esp. Repeatedly as applause. B strike (the hands) together in this way. 2 applaud thus. 3 put or place quickly or with determination (clapped him in prison; clap a tax on whisky). 4 (foll. By on) give a friendly slap (clapped him on the back). —n. 1 act of clapping, esp. As applause. 2 explosive sound, esp. Of thunder. 3 slap, pat.  clap eyes on colloq. See. [old english]