Green’s Dictionary of Slang

1. (US black) a state of being.

1938

Pittsburgh Courier (PA) 30 July 11/1: We tipped in here on a stranger riff, but the jitterbugs and ickies were stached in the auditorium.

2. (orig. US black) one’s personal style.

1944		D. Burley Orig. Hbk of Harlem Jive 150: Wrong riff: the wrong thing — either by words or action.
1959		D. Burley Diggeth Thou? 34: So after he had sounded and she had dug his riff, / She cut into his dommy and helped kill the fifth.
1978		R. Price Ladies’ Man (1985) 22: They weren’t hearing each other, just running their riffs.
1980		E. Folb Runnin’ Down Some Lines 210: The black disk jockey, with his patter or advertsing ‘riff’.
1999		Guardian Rev. 24 July 3: Lenny’s greatest riffs go into surreal fantasies where image follows image.
2000		C. Cook Robbers (2001) 346: His brain all over the place, making weird connections, circles and arcs, a stoned jazz riff.

3. (US black) a theme, a cause.

1957

J. Gelber Connection 95: Why didn’t you get on the H-Bomb riff? If you needed a riff.

4. (US) information.

1962		P. Crump Burn, Killer, Burn! 242: What’s to you and her, I mean, de riff?
1964		R.S. Gold Jazz Lex. xxii: A number of terms applied to human behavior are analogical extensions from properties of the music or musicians. Hence, riff and lick, originally a musical phrase or idea, are extended to mean any idea, plan, proposal, or situation.
2001		K. Sampson Outlaws (ms.) 111: I’ll give him the full riff about Thursday then.
2023		(con. 1962) J. Ellroy Enchanters 233: Babs Payton’s riff. Shelley Mandel in all guises. Penicillion peddler/call-girl hound.

5. a sudden action.

1960

Mad mag. Jan. 49: And then, in a quick riff, I dug on the roof.

6. (US) a joke, a line.

1978

R. Price Ladies’ Man (1985) 100: You were the fastest man [...] You had the baddest riffs.

7. (US) an argument.

1971		E.E. Landy Underground Dict. (1972).
1983		R. Price Breaks 52: I got into a riff with the waitress.

8. (orig. US black) familiar or habitual words, or music.

1971		(con. 1960s) D. Wells Night People 103: All bands have a little personal riff. It’s used to attract attention [...] it’s whistled, or blown on a horn, or beat out on a piano.
1971		L. Bangs in Psychotic Reactions (1988) 7: We had a lotta zingy lingo when I was a tad – sharp riffs like ‘Right on!’ and ‘Peace, brother!’.
1980		E. Folb Runnin’ Down Some Lines 251: riff Familiar or habitual words.
1991		M. Myers et al. Wayne’s World [film script] I know! I’ll use the ‘may I help you’ riff.
1999		N. Cohn Yes We have No 216: The time-honoured riffs on freedom and self-discovery.
2013		R. Hobbs ‘Brass’ in ThugLit Feb. [ebook] That's what everybody called them—Vincent and Mancini, like they were some sort of Abbott and Costello riff.

9. (US campus) one who takes advantage of another person.

1981

Eble Campus Sl. Mar. 6: riff – person who takes advantage of another.

10. a rumour.

2001

K. Sampson Outlaws (ms.) 91: Come back with all kinds of gold. That’s the riff at least, anyway.