Green’s Dictionary of Slang

(orig. Aus.) a challenge.

1885		Bulletin (Sydney) 13 Jun. 14/2: R. Matthews, the young American boxer, […] threw out the following ‘defi.’ upon his arrival in Maoriland: – That he was open to box any heavy weight in New Zealand to a finish for from £10 to £100 […]. The challenge was duly taken up […].
1890		Nat. Police Gaz. (NY) 29 Mar. 11/3: The defi is more directly issued to James J. Corbett, who gained considerable notoriety by his besting Jake Kilrain in a 6-round glove contest.
1904		Sun. Times (Perth) 17 Jan. 2/6: A coloured patron of the recent Dunne-Duggan mill [...] is out with a challenge to box any heavyweight in the State [...] Joe Cullen accepted the defi. on the spot.
1930		E.H. Lavine Third Degree (1931) 90: Some years ago a Hip Sing was sent to paste, on a neutral sign board, a defi to the On Leongs.
1960, 1975		Wentworth & Flexner DAS.