Green’s Dictionary of Slang

(US) completely, absolutely, altogether.

1892		W. Norr Stories of Chinatown 6: I got stuck on her for fair.
1905		H. Green Actors’ Boarding House (1906) 127: On the dead, I t’ink I’m off me nut fur fair.
1911		‘Sing Sing No. 57,700’ My View on Books in N.Y. Times Mag. 30 Apr. 5/2: Don Quixote [...] The geezer that went with him was a fall-guy for fair.
1915		Wodehouse Psmith Journalist (1993) 171: He’s got a lot of dem for fair.
1927		D. Hammett ‘The Big Knockover’ Story Omnibus (1966) 306: These bimbos were a couple of lollipops for fair. There wouldn’t have been an ounce of fight in a ton of them.
1936		(con. 1920s) Dos Passos Big Money in USA (1966) 906: He said he’d be a poor homeless boy for fair if he didn’t get back to the office.
1951		J. Blake letter 21 June in Joint (1972) 22: I pointed out to him that he and his shillelah had put the heat on but good and fucked me up for fair.
1957		G. Metalious Peyton Place (1959) 325: The backbone of Chestnut Street is broken for fair.
1965		B. Jackson Get Your Ass in the Water (1974) 131: We chewed the rag for quite a while and shot the con for fair / and when it came to spreadin’ jive, you could gamble that I was there.