Green’s Dictionary of Slang

1. (20C+ use mainly US) a penitentiary, spec. Millbank, London.

1873		C. Rampini Letters from Jamaica 23: Her term of ‘labour at the Penn’ as the negroes jocularly call it.
1879		Nat. Police Gaz. (NY) 20 Dec. 11/3: He was convicted and sent to the ‘Pen’.
1884		C.E. Craddock In the Tennessee Mountains 66: ‘What wat it ez happened at the Pen?’ [...] ‘They put him right inter the forge at the Pen, an’ he tuk ter the work like a pig ter carrots.’ The ex-convict [...] cast his eye disparagingly.
1899		J. Flynt Tramping with Tramps 105: I saw a man go into the Fort Madison ‘pen’.
1902		Globe (London) 25 Nov. 1/5: Newgate was known by its guests as ‘the Gate,’ Tothill Fields as ‘the Downs,’ and Millbank Penitentiary as ‘the Tench’ or ‘the Pen’.
1903		H. Hapgood Autobiog. of a Thief 38: If a thief wants to keep out of the ‘pen’ or ‘stir,’ (penitentiary) capital is a necessity.
1916		J. Lait ‘Charlie the Wolf’ Beef, Iron and Wine (1917) 57: This here is a dangerous young can’idate for the pen.
1926		J. Tully Jarnegan (1928) 152: I got word that the Warden at that Eastern pen would give me every facility to make a great prison picture there.
1934		(con. 1920s) J.T. Farrell Young Manhood in Studs Lonigan (1936) 257: He saw himself in the pen for a manslaughter charge.
1946		Mezzrow & Wolfe Really the Blues 44: I had done two bits in the pen.
1959		C. Himes Crazy Kill 74: Looks a little like Country Boy used to look ’fore they sent him to the pen.
1969		‘Iceberg Slim’ Pimp 43: Your Honour, don’t send me to the pen.
1974		V.E. Smith Jones Men 53: They know people don’t like it in the pen.
1984		B. Ellem Doing Time 193: pen: short for penitentiary or prison.
1988		Ice-T ‘Grand Larceny’ 🎵 The only way to stop the stealin’ / Is throw me in the pen.
1993		Dr Dre ‘Stranded on Death Row’ 🎵 To my motherfuckin homies doin time In the pen and the county jail / Mobbin with your blues on, mad as hell.
2005		D. Nelson Inner Piece 37: The Graybar Hotel. The Joint. Stir. ‘Q’. The Pen. Most of these names he’d heard before.
2011		S. Kelman Pigeon English 139: My auntie taught me, she learned it [i.e. forgery] in the pen.
2011		W. Henderson City of Nightmares pt 2 v: The Pen ain’t safe dark hours of the night, / they might want a see if your ass really tight.
2013		K. Koke ‘Bring Me Down (Intro)’ 🎵 Please friend, I don't wanna squeeze 10 / I wanna make g’s I don't wanna see pen.
2019		C.D. Rosales Word Is Bone [ebook] He looked hard, man. Like homies look right after they been let out the pen.
2020		G. Krauze What They Was 14: [F]resh out of pen after a year and a half .
2023		F. Bill Back to the Dirt 113: [H]e used his connections from the pen.

2. (US) a holding cell in a police station or courthouse.

1906		A. Train Prisoner at the Bar 241: The judge having delivered his charge, and the jury having [...] retired to the jury-room, a court officer claps the prisoner upon the shoulder and leads him away to the prison pen.
1932		Seabury Report 72: [of a courthouse] Ordinarily, a court attendant is in charge of the detention pen in which the prisoners are kept, waiting arraignment or trial.
1965		H. Williamson Hustler 176: They got me down to the station, took me back and put me in the pen.
1975		Sepe & Telano Cop Team 149: Frankie was booked for burglary and lodged in the precinct pen.