Green’s Dictionary of Slang

1. (US) a cunning or dishonest person, usu. of a businessman, a shrewd and predatory lawyer, a confidence trickster.

1891		Hazel Green Herald (Wolfe Co., KY) 3 July 8/1: Say ‘Slicker,’ has your quill got so slick that you can’t scratch?
1900		Flynt & Walton Powers That Prey 79: I vant mein money back. I loose two dollar. Dose fellows is slickers.
1911		L. Pound ‘A Second Word-List From Nebraska’ in DN III:vii 547: slicker, n. A sharper, or cheat. ‘He is a slicker.’.
1918		Johnston McCulley ‘Thubway Tham’s Inthane Moment’ in Detective Story 19 Nov. 🌐 I reckon these New York slickers don’t get gay with me!
1929		V.W. Saul ‘Vocab. of Bums’ in AS IV:5 344: Slicker—A skillful crook.
1938		H. Asbury Sucker’s Progress 233: A sizable portion of the ‘stuff’ that these slickers of the steamboats squeezed from the pockets of gullible travelers went for fancy clothing, for the river gambler of the 1840’s and the 1850’s [...] was perhaps the gaudiest and most picturesque dresser of his day; compared to him the New York dude [...] was a veritable scarecrow.
a.1946		‘The Open Book’ in G. Logsdon Whorehouse Bells Were Ringing (1995) 115: Now there’s boosters from poor Oklahoma, / And there’s brokers from old Arkansaw; / But they’re cotton pickers and tinhorn dice slickers, / With none too much sand in the craw.
1955		‘Blackie’ Audett Rap Sheet 158: They made quite a joke about her having to get in the F.B.I. to keep an eye peeled for card-slickers.
1960		C. Himes Big Gold Dream 100: It doesn’t belong to you, slicker.
1972		D. Pendleton Boston Blitz (1974) 39: The guy’s a slicker.
1986		F. Taylor Auf Wiedersehen Pet Two 129: Country pads for city slickers.
1991		B. Hamper Rivethead (1992) 148: He was only a conglomeration of the hucksters and slickers around him.
2000		Indep. on Sun. Rev. 23 Jan. 24: If you can’t tell a slicker from a fobber.
2015		P. Beatty Sellout (2016) 27: Dickens shall remain free of [...] Frenchmen, redheads, city slickers, and unskilled Jews.

2. (US) one who avoids war service by obtaining a government or civil service job.

1918

Godwin’s Wkly (Salt Lake City, UT) 26 Jan. n.p.: The slicker is a slacker who is smart enough to get a bomb-proof position that will entitle him [to] be, inferentially, in drawing-room and clubs, a hero.

3. (US) ext. of sense 2 above, a socially sophisticated, wordly individual.

1920		F.S. Fitzgerald This Side of Paradise in Bodley Head Scott Fitzgerald III (1960) 43: The slicker was good–looking or clean-looking; he had brains, social brains that is, and he used all means on the broad path of honesty to get ahead, be popular, admired and never in trouble. He dressed well, was particularly neat in appearance, and derived his name from the fact that his hair was inevitably worn short, soaked in water or tonic, and slicked back as the current of fashion dictated.
1935		O.O. McIntyre ‘New York Day by Day’ 5 June [synd. col.] All this on the street of slickers with a game that was a bilk when the 49-ers swarmed the Yukon.
1949		‘F. Bonnamy’ Blood and Thirsty (1952) 201: If those city slickers aren’t careful, they’ll be working as stevedores.
1950		Goldin et al. DAUL 197/2: Slicker. [...] 2. A shrewd person sophisticated in the underworld; a city dweller as differentiated from a hoosler.
1954		North. Standard (Darwin, NT) 9 Dec. 9/3: A pen picture of the meeting between the bushman and the city slicker.
1964		R. Abrahams Deep Down In The Jungle 232: Damn, those city slickers sure do chew some nasty smelling tobacco.
1971		Ed Bullins ‘Dandy’ in King Black Short Story Anthol. (1972) 75: I guess she thinks I’m a slicker.

4. (orig. US) a dandy, a smart dresser.

1922–24		O.O. McIntyre White Light Nights 9: Always their victim is the New Yorker—the wise-cracking slicker.
1927		D. Hammett ‘The big Knockover’ Story Omnibus (1966) 276: ‘And the slicker with his back to us?’ I probed.
1932		(con. 1910s) J.T.Farrell Young Lonigan in Studs Lonigan (1936) 109: Swan, the slicker, who wore a tout’s grey checked suit with narrow-cuffed trousers, a pink silk shirt with soft collar, and a loud purplish tie.
1947		in G. Legman Limerick (1953) 183: She’d married a slicker / Who stuck to his liquor / And scorned her ripe maraschino.
1960		J. Iggulden Storms of Summer 34: She’s been [...] waiting for a smooth slicker like you to turn up.
1968		N. Heard Howard Street 37: These so-called slickers and thoroughbreds don’t mean him no good.
1999		Guardian Guide 26 June–2 July 54: The slickers who learn what a man’s gotta do.
2000		Indep. Rev. 9 June 9: A slicker like you, with that ridiculous tussock of a beard. I bet you fancy yourself as a ladies’ man.

5. a smooth, plausible person, esp. in the context of seduction.

1953

J. Thompson Savage Night (1991) 12: You know what you are? [...] You’re a slicker.