Green’s Dictionary of Slang

1. (US, also g.b.) a $1 bill; usu. in pl.

1862		in R.G. Carter Four Brothers in Blue (1978) 20 Aug. 83: A show of greenbacks procured a man’s discharge from the service as easy as tumbling off a log.
1866		Night Side of N.Y. 37: He woke up somewhere next morning minus four thousand dollars in bonds and greenbacks.
1866		Sportsman 18 Dec. 2/1: Notes on News [...] America, the land of freedom, green-backs, and ‘shoddy’ millionaires.
1871		Galaxy (N.Y.) May 654: When Congress authorized the present issue of greenbacks, the Treasury Department executed plates of enormous cost and wonderful workmanship, from which the whole amount of currency authorized by Congress was to be printed.
1882		G.A. Sala in Living London (1883) Mar. 115: To the American Civil War the Lingua Balatronica owes the revival, if not the invention, of [...]‘greenback’.
1887		G. Devol Forty Years a Gambler 121: They did not find out who it was that won the greenbacks.
1890		A.C. Gunter Miss Nobody of Nowhere 228: Gussie can hear the crinkle of the greenbacks as he folds them up.
1900		Flynt & Walton Powers That Prey 2: James Dison of the naughty city found himself possessed of a roll of ‘greenbacks’ and of a handsome watch.
1912		J.W. Johnson Autobiog. of an Ex-Coloured Man (1927) 58: I then drew from under the pillow my precious roll of greenbacks.
1914		Sport (Adelaide) 22 May 4/7: [They] pught to hurry up and get spliced or they will be too ancient to get any [...] greenbacks.
1929		W.R. Burnett Little Caesar (1932) 39: Tony saw pack after pack of wrapped greenbacks drop into the sacks.
1936		L. Dent ‘Angelfish’ in Goulart (1967) 224: His long forefinger raked out loose greenbacks.
1949		H. Miller Sexus (1969) 174: He fished out a roll of greenbacks, flipped them under my nose.
1957		C. Himes Imabelle 22: Changing greenbacks into silver dollars and banking the cuts.
1965		C. Himes Rage in Harlem (1969) 23: [as 1957].
1978		A. Maupin Tales of the City (1984) 179: I don’t give a damn about a greenback dollar.
1989		(con. 1968) W.E. Merritt Where the Rivers Ran Backward 157: Calvin paid with orange paper. Military payment certificates. The army wouldn’t give us greenbacks.
1992		K. Lette Llama Parlour 87: He followed, close behind, dealing out greenbacks to all the people I’d kicked or scratched during my departure.
2005		J. Stahl I, Fatty 187: The clerk just stink-eyed the greenback.
2012		T.P. McCauley ‘Lady Madeline’s Dive’ in ThugLit Sept./Oct. [ebook] About two grand in greenbacks.
2013		K. Sampson Killing Pool 78: Two bags [...] each containing a few hundred grand to be changed into crispy US greenbacks.

2. (Aus./UK/Irish) a £1 note.

1876		G. Lander Little Gerty III ii: By the powers! [...] hand me over one o’ them greenbacks.
1959		A. Sillitoe ‘Loneliness of the Long-Distance Runner’ Loneliness of the Long-Distance Runner (1960) 34: Three greenbacks as well had been washed down by the water.
1965		L. Dunne Goodbye to The Hill (1966) 125: Those two greenbacks were burning a hole in my pocket.
1991		F. Mac Anna Last of the High Kings 84: He smiled and thought about envelopes packed with greenbacks.
1994		(con. 1970s) G. Byrne Pictures in my Head 66: Greenbacks in our pockets courtesy of the P & T.