Green’s Dictionary of Slang

1. a blow, usu. from a fist; also fig. use.

1932		(con. 1910s) J.T. Farrell Young Lonigan in Studs Lonigan (1936) 30: Did you see Doneggan take a wham at TB?
1947		in G. Legman Limerick (1953) 20: There was a young man from Siam / Who said, ‘I go in with a wham, / But I soon lose my starch / Like the mad month of March, / And the lion comes out like a lamb.’.
1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 78: ‘Well, there’s a wig’ (tousling person’s hair), ‘and there’s a wham’ (in person’s stomach).
1974		Eble Campus Sl. Mar. 6: wham (v. or n.) – cutting, hostile or contemptuous remark.

2. (US black) a large, aggressive man.

1983

R. Klein Jailhouse Jargon and Street Sl. [unpub. ms.].

3. an unpleasant woman.

1986

Eble Campus Sl. Mar. 11: wham – a woman who does harm to men, emotionally or physically.