Green’s Dictionary of Slang

1. (Aus.) an acquaintance, a friend.

1894		Truth (Sydney) 17 June 1/8: They next thing I knew was the the reins were in my hands and my noble had vanished.
1911		E. Dyson ‘On a Bender’ in Benno and Some of the Push 76: So me noble drifted from bad t’ worse. ’Oh, my!’ ’n’ afore night he was all sorts.
1935		C. Drew ‘Buckled’ in Bulletin 29 May 48/2: ‘Hello, me noble,’ says I, ‘What are you doin’ so far from the city?’.

2. (US) a man hired as a guard to protect strike-breakers.

1927		(con. 1911) H. Asbury Gangs of N.Y. 362: They were called finks, while the gunmen who protected them were known as nobles.
1949		Monteleone Criminal Sl. (rev. edn).
1950		Goldin et al. DAUL 145/2: Noble. (Rare) A guard hired to protect strike-breakers.

3. (US) the boss of a gang of such guards.

1952

(con. 1920s) ‘Harry Grey’ Hoods (1953) 266: ‘We’re nobles [...] Nobles get sixteen bucks a day. We’re like the bosses over the finks.’.

4. (US prison) an inmate considered to be reliable, trustworthy by the guards.

1966

‘Return of Honky-Tonk Bud’ in D. Wepman et al. Life (1976) 61: Those real boss meals are eaten by wheels, / Nobles and all of that jazz.