Green’s Dictionary of Slang

1. (US/Can. Und.) a night watchman.

1914		Jackson & Hellyer Vocab. Criminal Sl.
1933		Ersine Und. and Prison Sl.
1950		Goldin et al. DAUL 90/1: Hack, n. [...] 2. A watchman.

2. (orig. US) a police officer.

1915		Morn. Tulsa Dly World (OK) 13 June 19/1: Day hack — Policeman on day duty.
1924		G. Henderson Keys to Crookdom 414: Police. [...] shack, hack.
1939		R. Chandler Big Sleep 204: A very smart cagey guy who tries [...] to give the impression he’s a middle-aged hack fed up with his job.
1941		‘Digg Mee’ ‘Observation Post’ in N.Y. Age 25 Oct. 9/5: Can’t anything stop you but the ‘hack’? You’re speeding, jack.
1979		F. Norman Too Many Crooks Spoil the Caper 171: There was nothing new in Scotland Yard hacks knocking back a few with the chaps.

3. (US black) a generic term for any white person.

1934

J.L. Kuethe ‘Prison Parlance’ in AS IX:1 26: hack. A white person.

4. (US/Can. Und.) a prison guard; a warder.

1931		G. Milburn ‘Convicts’ Jargon’ in AS VI:6 439: hack, n. A prison guard.
1934		L. Berg Prison Nurse (1964) 58: No hack can make a monkey out of me.
1946		Mezzrow & Wolfe Really the Blues 314: Some mean hack of a keeper nabs a colored boy on the coal line for snitching a loaf of bread.
a.1953		‘Death Row’ in D. Wepman et al. Life (1976) 118: I lay on my bunk, trying to smoke, / And listened to a hack tell a dirty joke.
1960		C. Cooper Jr Scene (1996) 261: You want the hack to come in and lock ever’body in them goddam cells?
1975		E. Torres Carlito’s Way 19: Even the hacks would check out a beef with Earl.
1983		N. Heard House of Slammers 18: Jamison was not the kind of hack who would run headlong into the fray at head-whipping time.
1992		R. Marcinko Rogue Warrior (1993) 367: No one bothers me—guards included (they’re known colloquially as hacks, which stands for Horse’s Ass Carrying Keys).
2000		Other Side of the Wall: Prisoner’s Dict. July 🌐 Hack: A correctional officer.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 83/1: hack n. a prison officer.
2009		J. Stahl Pain Killers 17: You didn’t get to be gift shop trustee by slipping the hacks free cup holders.
2017		T. Pluck Bad Boy Boogie [ebook] The hacks said they should’ve backed the ambulance over her, put the woman out of her misery.
2022		J. Hannaham Didn’t Nobody Give a Shit 42: The hacks of Ithaca had given her a voucher for a one-way ticket.

5. a bodyguard.

1989

(con. 1950s–60s) in G. Tremlett Little Legs 194: hack a minder.