Green’s Dictionary of Slang

1. (US black) the human shoulder.

1943		D. Burley N.Y. Amsterdam Star-News 24 Apr. 11: The shoulders [of a zoot suit] are what they call braced broads.
1944		D. Burley Orig. Hbk of Harlem Jive 104: His hideaways were slashed like canteloupe; his broads were stacked like John the Conqueror.

2. (US) the buttocks, the posterior.

1958		A,M, Harris Tall Man n.p.: ‘What about the blokes sitting on their broads in Seoul?’ [Simes:DLSS].
1972		B. Rodgers Quuens’ Vernacular 23: ‘His head says “no”, but his broad really wants that dick’.