Green’s Dictionary of Slang

copper n.

1. [late 18C+] (US, also copperskin, Mr Copperskin) a Native American; also attrib.

2. as money.

(a) [late 18C+] a halfpenny; thus coppers, mixed pennies and halfpennies.

(b) [late 18C+] (US) a cent.

(c) [1930s] in pl., wages.

(d) [1970s] (W.I.) in pl., money in general.

3. [mid-19C+] a police officer [the SE copper badges carried by New York City’s first police sergeants; patrolmen had brass badges, lieutenants and captains silver ones; strengthened by cop v. (1)].

4. attrib. use of sense 3.

5. [late 19C+] an informer, whether in or out of prison.

6. [20C+] (US prison) good conduct marks.

7. [1920s] a private detective.

8. [1940s] (US Und./police) ext. of sense 6, parole.

9. see copperhead n. (3)

In compounds

copper-hearted (adj.) (US Und.)

1. [mid-19C–1960s] being an informer by nature; thus turn copper-hearted, to betray one’s associates.

2. [1930s+] mean, vicious, adhering to the negative stereotypes of the police.

copper house (n.)

[1930s] a police station.

copper jitters (n.)

[1950s] (US drugs/Und.) excessive fear of the police, verging on obsession.

copper john (n.) (US Und.)

1. [1910s] a prison warden.

2. [1920s-30s] a prison.

3. [1940s] an informer.

coppernob (n.)

[1910s; 1950s] (UK juv.) a police officer.

coppershy (adj.)

[20C+] (US Und.) used of one who is terrified of the police.

copperskin (n.)

see sense 1 above.

copper’s nark (n.) [nark n.1 (1)]

[late 19C+] a police informer.

copper’s shanty (n.)

[late 19C] a police station.

copper-stick (n.) [note SE copper-stick, used to stir a laundry]

1. [19C] a police truncheon.

2. the penis [fig. use of sense 1 + stick n. (1a)].

In phrases

blow one’s copper (v.)

[1930s+] (US prison) to lose the reduction in sentence that would otherwise accrue for good conduct; thus hold one’s copper, to maintain good conduct.

call copper (v.) (also scream copper)

[1930s+] (UK Und.) to inform the police.

come (the) copper (v.)

[1930s+] to become an informer.

cry copper (v.)

[late 19C+] to raise the alarm.

give birth to a copper (v.) (also give birth (to it)) [fig. use of sense 3 above]

[1990s+] (Aus.) to defecate.

half-copper (n.) [19C]

(US) a half-cent.

play copper (v.)

[1900s] (UK Und.) to inform (on).

put the copper on (v.)

[1910s] (UK Und.) to inform against.

turn copper (v.)

[late 19C–1950s] (US) to become an informer.