Green’s Dictionary of Slang

1. a thief or swindler.

1709		Cibber Rival Fools I i: I was in with all the top Gamesters, and when there was a fat Squire to be fleec’d, I had my Office among then too; and tho’ I say it, was one of the neatest Operators about Town.
1872		E. Crapsey Nether Side of NY 21: Confidence-operators exist only because fools and their money can be easily parted.
1874		‘A.P.’ [Arthur Pember] Mysteries and Miseries 57: He moved about with [...] a nervous quickness which at once proclaimed him a skillful operator.
1940		J.H. O’Hara Pal Joey 79: She is a very smart little operator.
1940		D. Maurer Big Con 91: The insideman is almost always a better operator than the roper.
1959		G. Sparrow Great Swindlers 92: In the end Henry was no longer a big operator. He was reduced to asking for small sums and telling even larger lies to procure them .

2. the controller of a gambling game.

1804		Sporting Mag. May XXIV 125/1: The operator, who deals the cards at faro, or any other cheating game.
1924		‘Digit’ Confessions of a Twentieth Century Hobo 54: We watched for some time, but no one won a bet of any amount save the ‘operator’.
1949		G.G. Carlson ‘Argot of Number Gambling’ in AS XXIV:3 192: operator. The employee of a policy house who conducts the drawing. The term is frequently used also for an individual who owns a number gambling establishment.
1959		(con. 1900-29) L. Katcher Big Bankroll 320: He operated a casual ‘floating’ game and this was one such. It is part of the code of gambling that, in a game such as this, the operator is technically the ‘host’ .

3. (UK Und.) a pickpocket.

1821		W.T. Moncrieff Tom and Jerry I iv: Dukes and dealers in queer – heavy plodders and operators – noblemen and yokels.
1835		G. Kent Modern Flash Dict.
1848		Flash Dict. in Sinks of London Laid Open.

4. (orig. US, also operative) a person who pursues success, often ruthlessly or manipulatively.

1872		J.D. McCabe Lights & Shadows 285: The great operators plunder and destroy their lesser rivals without a feeling of remorse, and [...] blast the prospects and ruin the lives of scores whose greatest fault is an inability to oppose them successfully.
1875		North Amer. Rev. Jan. 157: An operator in Wall Street, and a professional gambler — he now dabbled in municipal politics much as he might have done in an exciting game of chance.
1901		W.S. Walker In the Blood 100: At one time he was classed as an ‘operative,’ and as such possessed of the means of self-support.
1938		D. Runyon ‘A Very Honorable Guy’ in Runyon on Broadway (1954) 417: He is well known [...] as a very large operator in gambling.
1948		(con. 1944) N. Mailer Naked and Dead 243: The whole thing was pathetic [...] Conn, the big operator.
1953		‘William Lee’ Junkie (1966) 125: There are big operators with political connections [...] usually police chiefs or other high officials.
1969		N. Cohn Awopbop. (1970) 41: By nature, he was an operator and he was always going to be successful.
1977		(con. 1960s) D. Goines Black Gangster (1991) 90: He was what I call an operator – the leader who involves weak and dull boys in vice.
1983		A-Team Storybook 45: Those hick pomegranate farmers were no match for an operator like him.
1999		Indep. Rev. 23 June 11: A sleek operator [...] who goes through life falsely raising people’s hopes for the casual delight of watching them dashed.
2000		Indep. Rev. 2 Feb. 7: It makes me sound like a dodgy operator.
2008		R. Price Lush Life 79: Ike, he’s like the street mayor or something. A real operator .

5. a major criminal.

1872		J.D. McCabe Lights & Shadows 367: Whatever other foolishness they may commit, these adroit operators never kill the goose that lays their golden eggs.
1928		‘J. Barbican’ Confessions of a Rum-Runner in Hamilton Men of the Und. 186: Izzay has no more to do with the big operators.
1938		D. Runyon ‘The Three Wise Guys’ in Runyon on Broadway (1954) 398: A phenomenal record for an operator as extensive as Blondy.
1949		W.R. Burnett Asphalt Jungle in Four Novels (1984) 130: He was a very, very big operator.
1955		B. Schulberg On the Waterfront (1964) 176: You were either a big operator [...] or a petty heister.
1963		M. Spillane Return of the Hood 41: Penny Stipetto had been on the verge of being a big time operator when he was knocked off.
1972		P. Fordham Inside the Und. 34: I [...] knew him for a good operator.
1998		I. Welsh Filth 140: Big operators flooding the city with smack.
2000		Observer Mag. 14 May 19: Smart operators like Cocky are only in it for the (huge amounts) of money.
2013		T. Piccirilli Last Whisper in the Dark 84: He was playing high-stakes poker [...] with Danny Thompson and the other big gun operators.

6. (US) a private detective; an informer.

1912		A. Train Courts, Criminals & the Camorra 112: There are in the city of New York [...] about one hundred and fifty licensed detectives. Under the detective license laws each of these [...] [may] employ as many ‘operators’ as he chooses.
1949		R. Chandler Little Sister 42: Going to a lone-wolf operator you never heard of.

7. a successful seducer of women.

1943		W.R. Burnett Nobody Lives for Ever 53: ‘[T]his dame’s loaded with money and Jim’s quite an operator. Suppose he marries her—then what?’.
1949		N. Algren Man with the Golden Arm 109: He’d always been a swifter and surer operator with women than Frankie.
1960		C. MacInnes Mr Love and Justice (1964) 71: Sharp operators! And the girls know?
1966		Trimble 5000 Adult Sex Words and Phrases.
1974		E. Wilson Show Business Laid Bare 188: give credit to men who are great operators, as we once called them, with the girls.
1996		(con. 1949) G. Pelecanos Big Blowdown (1999) 298: There’s gonna be plenty of girls. Plenty of girls for an operator like you.