badmouth, n. — Green’s Dictionary of Slang

badmouth n.

[SE but note Mandingo dajugu, bad mouth]

(orig. US black/W.I.)

1. a curse, a spell.

1938		Sat. Eve. Post Stories of 1938 175: So when, one afternoon, he got no fish [...] he decided Jenny Wee had put the bad mouth on him just by being near by.
1960		C. Cooper Jr Scene (1996) 6: Rudy wondered how the bad mouth about him had started.
1965		C. Brown Manchild in the Promised Land (1969) 301: I could tell her about the bad mouth, because this was something she knew.
1984		C. White Life and Times of Little Richard 22: One lady put the bad-mouth on me – like putting on a curse – that I would die at twenty-one.

2. one who talks maliciously or argumentatively.

1968		N.Y. Mag. 1 July 58/1: Disappointingly, this hot-headed bad-mouth turns out to be nothing but the voice of Ellison’s own favorite [...] character, himself.
1978		S. King Stand (1990) 1094: All ther hecklers and badmouths.
1980		E. Folb Runnin’ Down Some Lines 228: bad mouth One who talks in a provocative, belligerent, or argumentative manner. 2. One who talks badly about others.
2003		B. Gill Death of an Irish Lass 186: Could it be that she was a badmouth and [...] had the hammer out on everybody?

3. malicious gossip.

1972		D. Jenkins Semi-Tough 104: Like if she would change in any way and start putting a lot of bad-mouth on a man for some reason.
1980		E. Folb Runnin’ Down Some Lines 44: Lame talk refers to bad talk, in the sense of provocative or belligerent dialog. Expressions like smart mouth, fat mouth, foul mouth and bad mouth.
1993		T. Winton Lockie Leonard: Scumbuster (1995) 132: I’m copping a bit of bad-mouth myself.

put the bad mouth on (v.)

1. to vilify.

1955		Atlantic 195 45/2: Even Mrs. Clara and old big-head David don’t put the bad-mouth on him any more.
1961		Jet 12 Jan. 43: The bad mouth being put on those Negro teachers in New Orleans who declare they prefer ‘cultural’ things to integration.
1965		H. Rhodes Chosen Few (1966) 47: Mess with me and I’ll put th’ bad mouth on you down at th’ nurses’ home.
1971		H.E. Roberts Third Ear n.p.: bad mouth n. the telling of stories that may be true, but which reflect adversely on a person’s character or reputation; e.g. He’s putting the bad mouth on her now.
1978		A. Maupin Tales of the City (1984) 89: His son-in-law put the badmouth on me, and the old man tossed me out on my can.

2. to render unacceptable.

1969

E. Schiddel Good Time Coming 408: All I ever had was half a fix and a sniff, and that put the bad mouth on it for me forever.