Green’s Dictionary of Slang

broad n.2

[early black use, c.1930s, added to an implication of a shapely, well-built woman (cf. brace of broads under brace of... n.), although this may have been a pun on the mainstream use); Gold, A Jazz Lexicon (1964), also suggests link to SE broad-minded]

1. [1910s] (US Und.) a female confederate.

2. [1910s+] (mainly US) a prostitute.

3. [1910s+] (orig. US) a woman; the implication is of promiscuity.

4. [1920s] (US Und.) in cards, the queen.

5. [1940s+] (US prison, also broadski) an effeminate male homosexual, often a prostitute; thus broad squad, a ‘team’ of homosexuals.

6. [1940s+] (US campus, also brodie) an attractive woman.

7. [1970s+] (US gay) the buttocks.

In phrases

beating the broads (n.) [‘Broad is derived from the far-fetched metaphor of meal ticket, signifying a female provider for a pimp, from the fanciful correspondence of a meal ticket to a railroad or other ticket [and thus] a conductor’s hat check’ Jackson & Hellyer (1914)]

[1910s] (US Und.) corrupting a conductor on any form of transportation line.

house broad (n.)

[1940s] (US) a prostitute who lives and works in a hotel.

square broad (n.) [square adj. (2)]

[1940s–70s] (US black/Und.) any woman who is not a prostitute.

tipping the broads (n.) [see beating the broads ]

[1910s] (US Und.) riding on a purchased transportation ticket.