Green’s Dictionary of Slang

1. the index finger.

1935

A.J. Pollock Und. Speaks.

2. (US, also triggerboy, trigger guy, trigger tripper) a gunman, esp. one working for organized crime.

1930		Dly News (NY) 20 Oct. 4/4: The police [hope] that they might convict the trigger-men who fired four bullets into the gangster.
1939		Howsley Argot: Dict. of Und. Sl. 53: trigger, triggerman – a ‘gangster’ killer.
1945		L. Hoban ‘Time to Kill’ Crack Detective Jan. 🌐 When I opened the compartment door, I saw the trigger guy in the beaverskin coming toward me.
1947		W.D. Overholser Buckaroo’s Code (1948) 48: I’d rather have you on my side than ahalf-dozen of Harriman’s trigger trippers.
1949		Monteleone Criminal Sl. (rev. edn) 243: trigger man [...] an assassin; one who does the killing for a mobster gang.
1953		F. Paley Rumble on the Docks (1955) 27: The dock bosses with their shiv men and trigger boys.
1955		B. Schulberg On the Waterfront (1964) 69: Even when he was looking down the business end of a triggerboy’s .38.
1957		P. Rabe Agreement to Kill (2006) 231: You mean you never heard of Loma [...] He’s a trigger man.
1962		Ragen & Finston World’s Toughest Prison 822: trigger man – An assassin or gunman.
1978		R. Caron Go-Boy! 270: I wonder how much the trigger man got for his end?
1983		(con. 1970) S. Wright Meditations in Green (1985) 54: A former Green Beret staff sergeant, ex-Operation Phoenix triggerman, and recently promoted captain.
1990		M. McAlary Crack War (1991) 154: Most of the detectives believed Scott to be the trigger man.
2006		C. Carr Our Town 316: The Deeters also believed Cameron to be the triggerman who killed Claude.
2012		A. Bergen ‘Dread Fellow Churls’ in Crime Factory: Hard Labour [ebook] My triggerman was chewing on something.

3. an armed bodyguard.

1946		Mezzrow & Wolfe Really the Blues 24: A couple of trigger men always trailing along at his elbows.
1990		(con. early 1950s) J. Ellroy L.A. Confidential 22: Lee Vachss, contract trigger employed by Cohen.
1997		E. Little Another Day in Paradise 132: Fuck you and your triggerman here.

4. that member of a criminal gang who uses a gun.

1952		C. Hamilton Men of the Und. 203: You merely [...] slipped a hundred bucks in the triggerman’s pocket.
1961		Mad mag. Apr. 32: My older sister, Shirley, is married to a successful trigger man who is employed by a fine old firm of hoodlums.
1997		G. Sikes 8 Ball Chicks (1998) 29: Shygirl [...] peered at the group outside. One could be the triggerman.
2002		G. Pelecanos Hell to Pay 233: He was allegedly the triggerman in four murders by the time he was seventeen years old.
2009		L. McIlvanney All the Colours 312: [T]he police knew the story. Paramilitary organisation [...] likely triggerman.

5. (US prison) an armed prison guard.

1992

Bentley & Corbett Prison Sl. 97: Trigger A prison guard who carries or has access to a rifle or shotgun [...] generally used to indicate the prison guards manning the gun towers.

6. (Aus. teen) in pl., a hairstyle adopted by sharpie n.² girls c. 1971; it comprised a straggly fringe, sometimes bleached, situated in front of the ears.

2004

(con. 1960s-70s) T. Taylor Top Fellas 48/1: Girls would usually have a short frings and triggers — straggly bangs in front of the ears, often bleached.