noun Popular slang for gonorrhoea or, far less commonly, any sexually-transmitted infection.
The term clap–as applied to venereal disease–is of murky parentage, and thought to derive from either
(1) Provençal, clap, a heap of stones, from which rabbits made their homes, evolving in Old French to rabbit’s burrow, arriving in Middle English as clap(er) a brothel, or
(2) Middle French, clapoir, a bubo, referring to a venereal lesion
Note: Since buboes are not seen in gonorrhoea, the latter origin is unlikely according to JE Lighter Historical Dictionary of American Slang, Random House, 1994. Its use in the New World dates to 1587.
verb To strike the palmar surface of one hand with the other, usually understood as a way of demonstrating one’s approval of another person’s or party’s activity–e.g., acting, playing music, singing, dancing, etc.