Green’s Dictionary of Slang

1. a millimetre, esp. in the diameter of a tube or gun barrel [Latin, mille, thousand].

1877		Jrnl Anthropological Institute 6 21: The thickness of the cylindrical wall of the humerus is 20 millimeters. The extreme width at the condyles is 120 mill .
1946		C.B. Sheppard in Moore School Lectures (1985) 255: This is constructed in the form of a nearly closed C-shaped iron core with a scanning gap of about one mill width .
1960		E. Morgan You’re Long Time Dead 386: Sandy, I’ll be getting pictures of you in that outfit, don’t worry, as good as anyone can take – Best Man, What, on 35 mill? [OED].
1980		M. Bail Homesickness (1999) 19: ‘There was a film here.’ [...] ‘Sixteen-mill,’ Kaddock told them.
1998		P. Cornwell Point of Origin (1999) 113: Ball. Remington nine-mill.

2. a million, usu. dollars.

1914		Day Book (Chicago) 10 July 2/2: A law fixing a half mill levy for road-building so as to eliminate the ‘pork barrel’ system of legislation.
1938		W. Winchell On Broadway 16 Mar. [synd. col.] Some time ago we itemed that Life’s 1937 loss would be 3 ½ mill [...] The N.Y. Times reports Life lost $3,424,000.
1946		W. Winchell On Broadway 29 Mar. [synd. col.] Mike Todd is [...] readying a film to cost over two ‘mill.’.
1966		R.E. Alter Carny Kill (1993) 52: This place grossed thirty mill last year.
1979		E. Torres After Hours 129: House had to go for a quarter mill, easy.
1981		J. Wambaugh Glitter Dome (1982) 253: He’s only asking half a mill.
1987		C. Hiaasen Double Whammy (1990) 211: We’ve never dropped twenty-four mill before, Izzy.
1999		J. Baker Walking With Ghosts (2000) 5: I bet if it wasn’t two and a half mill you’d have paid him by now.
2000		Indep. Rev. 14 Mar. 1: The old Stock Exchange, when one flick of the nostril bought you ‘two mill of copper futures’.
2003		50 Cent ‘In da Club’ 🎵 I got a mill out the deal and I’m still on the grind.
2008		R. Price Lush Life 124: Twenty-five hundfred square feet, fourth floor, no elevator [...] Two point four mil .
2009		P. Temple Truth 242: As of last valuation, recession and all, the settlement’s now worth one point eight mill.
2011		J.J. Connolly Viva La Madness 157: You don’t come to London to collect three mill on your own.

3. (drugs) $1000 worth of heroin [Lat., mille, thousand].

1961

Rigney & Smith Real Bohemia xx: The purchases are made in cash: an ace ($1) [...] a yard ($100), and a mill ($1000).