Green’s Dictionary of Slang

1. (US Und./prison) an escapee, a fugitive; one who forfeits their bail bond; a deserter.

1902		Wash. Times (DC) 14 Sept. 10/4: Lamaster— A fugitive from justice.
1904		‘Number 1500’ Life In Sing Sing 250: Lamaster. Fugitive from justice; one who forfeits bail-bonds.
1910		J. Sullivan ‘Criminal Sl.’ in Amer. Law Rev. LII (1918) 889: A man who jumps his bail, becoming a fugitive from justice, is a ‘lamaster.’.
1916		‘Thieves’ Sl.’ Toronto Star 19 Jan. 2/5: BOND JUMPER Lamster.
1928		J. O’Connor Broadway Racketeers 253: Lammister — A fugitive from justice.
1929		C.G. Givens ‘Chatter of Guns’ in Sat. Eve. Post 13 Apr.; list extracted in AS VI:2 (1930) 133: lamster, n. Escaped convict.
1931		(con. 1910s) C.W. Willemse Behind The Green Lights 153: There also was a lamister from Harlem in the crowd.
1931		D. Runyon ‘The Lily of St. Pierre’ in Runyon on Broadway (1954) 139: Louie is a lammister out of Detroit on account of some job.
1931		W.N. Burns One-Way Ride 246: Lamster [...] meant ‘a guy who takes it on the lam’.
1938		D. Runyon ‘The Three Wise Guys’ in Runyon on Broadway (1954) 402: The Dutchman is generally a lammie from some place.
1940		D. Maurer Big Con 148: I’d sooner be a lamster any day.
1944		C.B. Davis Rebellion of Leo McGuire (1953) 194: I had to explain that a lamister was a guy on the lam.
1944		D. Runyon Runyon à la Carte 23: A lam-master from the Brush boys back home for over twenty years on an income-tax beef. [Ibid.] 29: The Reich is not interested in American lameroos.
1945		R.L. Bellem ‘Dead Don’t Dream’ in Hollywood Detective July 🌐 Tom Quillen was a lammister. A con who crushed out of stir back east.
1950		Goldin et al. DAUL 121/2: Lamester. One who jumps bail, escapes from prison, or in any manner becomes a fugitive from justice. [...] Lammie. See Lamester.
1950		P. Hoskins No Hiding Place! 191/1: Lamster. Deserter.
1952		Lait & Mortimer USA Confidential 98: His Rhode Island mobsters harbor lamisters from Gotham.
1953		‘William Lee’ Junkie (1966) 81: Tourists, servicemen, merchant seamen, gamblers, perverts, drifters, lamsters from every State in the Union.
1962		Ragen & Finston World’s Toughest Prison 807: lamster – A fugitive from justice.
1971		T. Thackrey Thief 292: I told him who I was and what I was – a lamster from California.
1990		S. Morgan Homeboy 319: Mushed into the subterraneous goo of lamister whore dreams.
2001		‘Randy Everhard’ Tattoo of a Naked Lady 155: It’s the right world to disappear in [...] Lamsters, parole jumpers, runaways, you name it.

2. (US Und.) a member of a pickpocket team who leaves with the loot.

1926

‘Und. and Its Vernacular’ in Clues mag. 158–62: lamster Member of pickpocket gang that leaves with the loot.