Green’s Dictionary of Slang

brother n.

1. [late 19C+] a general form of address to an unnamed male or self-reflexively.

2. [1910s+] a black male.

3. [1920s+] a form of address to a fellow black male.

4. [1960s+] (orig. US black) in pl., constr. with the, black people, orig. in 1960s black radical use, now used by both black and white speakers with only residual political overtones.

5. [1960s+] in pl., constr with the, one’s intimates, one’s close friends.

6. [1970s+] a non-black male accepted in the black community.

In compounds

brotherman (n.) (also brother man)

[1970s+] (US black) a fellow black man, usu. as a form of address.

In phrases

brother in black (n.)

[1930s–40s] (US black) a form of address from one black man to another; a black man; thus sister in black, n., a black woman.

SE in slang uses

In compounds

brother chip (n.) [19C]

1. a carpenter.

2. a fellow professional of any sort.

brother round-mouth (n.) [its ‘speech’ is a fart]

[early 19C] the anus.

brother starling (n.) (also brother socket) [SE brother + starling; ? the characteristics of the bird/socket n.]

[late 17C–19C] one who shares a friend’s mistress.

In phrases

brother (of the)... (n.)

see separate entry.

brother-where-are-you? (n.) (also brother-where-art-thou?) [his being ‘blind’ drunk]

[1920s] a drunkard.