Green’s Dictionary of Slang

1. notes, bills, paper money; also attrib.

1821		Egan Life in London (1830) 47: tom [...] smiled with indifference at the rolls of soft which his most captivating fancy-piece drew from him repeatedly.
1844		Henry Clay Bugle 11 Apr. 3/3: Mr. Tod [...] endorses the bank doctrines of Gov. Shannon, and declares himself a sort of hermaphrodite, soft money man [DA].
1851		‘Greenhorn’ [G. Thompson] Bristol Bill 40/2: He [...] told him he had ‘cracked’ something, no matter what — and he wanted to ‘smash’ a bunch of the ‘soft’.
1859		Hotten Dict. of Modern Sl. etc. 98: SOFT [...] formerly bank notes.
1860		R. Nicholson Rogue’s Progress (1966) 32: Hayward [...] carried on the system of passing ‘soft’ - that is to say, forged - notes on the Bank of England.
1865		Leaves from Diary of Celebrated Burglar 8/2: There was over three hundred pounds [...] mostly all in ‘soft’.
1873		Sl. Dict.
1879		New Ulm Rev. (MN) 19 Nov. 1/5: ‘Take the “soft” to the hotel, with the usual story’.
1893		W.S. Walsh Literary Curiosities 450: In political parlance, especially during the second half of the decade 1870–1880, [...] ‘soft money’ [...] was understood [to mean] an irredeemable paper currency such as was advocated by the Greenbackers.
1898		Omaha Dly Bee (NE) 15 Nov. 5/3: The ‘soft’ is paper money.
1905		Little Falls Herald (MN) 31 Mar. 3/3: How to Operate the Shell Game with Profit [...] When the steerer gets the geezer in the push, let the boosters stall until the main plugger cops; then, if the gilly digs in his keyser [sic] or goes south for soft, give him a flash of the little dinkie doodle ball.
1914		Jackson & Hellyer Vocab. Criminal Sl. 78: soft [...] Paper money [...] ‘I fanned a gob of soft in the right jerve.’.
1926		Maines & Grant Wise-crack Dict.
1933		‘Paul Cain’ Fast One (1936) 158: I’ve got Fenner’s cheque too and somewhere around ten grand soft.
1944		H.B. Hersey G.I. Laughs 171: Soft money, paper currency.
1950		Goldin et al. DAUL 201/2: Soft. (Carnival) Paper currency; bills.
1967		M. Braly On the Yard (2002) 87: Such a fifteenth, wrapped in wax paper, was sold either for three dollars soft money or a carton of cigarettes.
1983		R. Klein Jailhouse Jargon and Street Sl. [unpub. ms.].
1991		(con. 1920s) O.D. Brooks Legs 117: In case I pulled another rock and the next cop gave me a fast frisk, I exchanged the hard money for soft, rolled four ace notes tightly and buried them in the tobacco bag.
1998		T. Fontana ‘Strange Bedfellows’ Oz ser. 2 ep. 6 [TV script] How dumb you got to be to give hard or soft money for a decent place to crash and it’s false advertising?

2. (US) currency that is likely to lose its value.

1986

(con. 19C) Chapman NDAS.

3. (also soft dough) money that is easily earned or otherwise gained.

1913–14		Van Loan ‘No Business’ Taking the Count 156: Tierney says it will be the softest money that ever went hunting a home.
1920		A. Baer Sez ‘Bugs’ Baer 26 Aug. [synd. col.] Cap Huston doesn’t want to bilk Babe [Ruth] out of soft dough.
1949		Monteleone Criminal Sl. (rev. edn) 217: soft dough Money easily acquired.
1965		(con. 1940s) B. Behan Confessions 151: Sure [...] if it’s soft money.