Green’s Dictionary of Slang

1. an inexperienced workman used as a strike-breaker.

1890–1904

Farmer & Henley Sl. and Its Analogues.

2. (orig. US) a novice, an innocent, one who has newly arrived.

1875		B.E. Lloyd Lights and Shades in S.F. 207: Other country chaps may be greeners.
1888		Justice (London) 9 June n.p.: To extinguish the competition of the ‘greeners’ by prohibiting immigration of foreign paupers is rather a palliative than a remedy.
1892		I. Zangwill Children of the Ghetto 43: He was a ‘greener’ of the greenest order, having landed at the docks only a few hours ago.
1901		Boy’s Own Paper 18 May 514: It’s easy to see you’re no greener.
1912		E. Pugh City Of The World 270: But races is the snider’s picnic. Gets up like a greener, and asks one o’ the tick-tack boys to put a bit on for him.
1929		Hostetter & Beesley It’s a Racket! 226: greener — An immigrant; or, one who has just come to the city from the country.
1946		S. Jackson Indiscreet Guide to Soho 126: He [...] doesn’t like to think of the days when he came here as ‘a greener,’ knowing not a soul or a word in English.
1950		P. Hoskins No Hiding Place! 190/2: Greener. A man knowing nothing.
1977		(con. 1941) R. Beilby Gunner 15: I wouldn’t like to stop a charge of buckshot from that old Greener if anything starts.
1991		D. Widgery Some Lives! 184: Many of them, like myself, ‘greeners’ [newcomers], willing to work at anything.