Green’s Dictionary of Slang

1. (orig. US) illicit liquor, usu. whisky (other than during US Prohibition).

1900		Sun (NY) 14 Jan. 6/2: I thinks of thim [sic] old times of booze, whin tryin’ to down my bootleg [...] with an extry chew in my mouth to drive away the taste.
1922		Bridgeport Times (CT) 21 June 12/1: [headline] Pussyfoot Cusses Bootleg, Not Plain Ordinary Licker.
1939		Howsley Argot: Dict. of Und. Sl. 9: bootleg – contraband.
a.1948		(con. early 1930s) C. McKay Harlem Glory (1990) 39: This special bootleg was sold at 25 cents a bottle.
1960, 1975		Wentworth & Flexner DAS.
1965		(con. 1940s) Malcolm X Autobiog. (1968) 214: I was myself [...] supplying some lesser quantities of bootleg to reputable Harlem bars.

2. (US) adulterated coffee, usu. mixed with chicory.

1882		‘The Jargon of Thieves’ in Derry Jrnl 8 Sept. 6/5: Coffee is called ‘bootleg’ .
1888		N.Y. Herald 1 Apr. 9/6: When a very hard looking man said he wanted ‘boot leg and chuck’ [...] [he] turned on his heel and returned in about two minutes with a cup of coffee and a hunk of bread.
1893		J. Hawthorne Confessions of Convict 30: A cup of ‘boot-leg’ stands on the bracket.
1904		‘Number 1500’ Life In Sing Sing 20: A large piece of bread and a cup of the mixture locally honoured by the title of ‘bootleg,’ but appearing in the dietary scale as coffee.
1949		Monteleone Criminal Sl. (rev. edn) 31: bootleg Prison coffee; inferior coffee.
1960, 1975		Wentworth & Flexner DAS.

3. (US black) a bootlegger.

1960, 1975

Wentworth & Flexner DAS.

4. (orig. US) a bootleg or pirated record, tape or video etc.

1951		Record Changer Nov. 1 [heading] Victor presses bootlegs!
1971		It 2–16 June 18/1: This album of the [Jimi Hendrix] Experience recorded at the Albert Hall in ’69 is not a bootleg (although there’s an inferior bootleg in mono selling at the same price), it’s an official German release.
1979		Sounds 3 Mar. n.p.: ‘Van the Man’ bootleg [KH].
1983		K. Hudson Dict. of the Teenage Revolution 24: Bootleg. An illegal or pirated recording.
1999		Guardian G2 22 July 12: The batch of bootlegs that appear every time they perform.
2000		N. Barlay Crumple Zone 13: The first time he got arrested, rousted one rainy dawn on Moss Side with a roomful of bootlegs.

5. a song that is a mix of two completely different songs spliced into one.

2002		N.Y. Times 9 May n.p.: The songs, called mash-ups or bootlegs, typically match the rhythm, melody and underlying spirit of the instrumentals of one song with the a cappella vocals of another. And the more odd the pairing the better.
2004		Guardian 15 Aug. 🌐 As 2 Many DJs, Belgium’s Dewaele brothers spearheaded the vogue for bootleg mash-ups and recorded one of the most ingenious mix albums ever made.