Green’s Dictionary of Slang

1. one cigarette.

2005

(con. 1960s) Guardian Weekend 2 Apr. 24: He bought a ‘single,’ one lone cigarette from Tonibells for sixpence.

2. (US) a $1 bill.

1939		Howsley Argot: Dict. of Und. Sl.
1945		H.B. Darrach Jr. ‘Sticktown Nocturne’ in Baltimore Sun (MD) 12 Aug. A-1/3: Crowbar ‘wanted the single to grab a cab to the Union Hall’.

3. (US) a person, esp. a criminal, who works or lives alone.

1949		(con. 1930s) A. Hynd We Are the Public Enemies 33: Dillinger now became a single.
1971		B. Short Black and White Baby 251: From the Dutch Mill, I went to the taproom at the Hotel Plaza, as a single.
1987		A. Rollini Big Bands 122: He sang and played magnificently. [...] I believe that he is one of the best singles in the country.

4. (US Und.) for a prostitute, a single act of paid intercourse.

1963

in T.I. Rubin Sweet Daddy 46: I had some of my chicks bring in much as seventy-five or a hundred for a single.

5. (N.Z. prison) a 1-oz. pack of prison-issued tobacco.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 167/1: single n. a one-ounce packet of prison tobacco.