Green’s Dictionary of Slang

1. a knockout blow.

1900		Bulletin (Sydney) 27 Jan. 14/2: Holy Moses! a carpet snake about 10 feet long! He made a ‘dinny-aiser’ at my leg, but fortunately did not allow sufficiently for the extraordinary rapidity of my exit into the clearing.
1907		N.F. Spielvogel Cocky Farmer 14: I gets a dennyaiser in the eye, and sits down suddenly [AND].
1915		Sun. Times (Perth) 5 Sept. 8: I got kinder sick of him and dotted him a dinnyhaser in the custard and jelly.
1924		Sun. Times (Perth) 10 Aug. 17/8: ‘Filter’ scored one with a ‘dinnihazer’.
1934		C. Drew ‘Algy’ in Bulletin 8 Aug. 50/1: He stopped a dinnyhaser with his jaw.
1984		W. Ammon et al. Working Lives 85: Sometimes he let his dinnyhazer go with such viciousness.

2. a strenuous attempt.

1902		Bulletin (Sydney) 29 Nov. 31/2: When the darn thing was stoppin’ I makes a dinnyaiser to get out of it as I see others doin’. But they didn’t land like me at all.
1905		Bulletin (Sydney) 14 Dec. 32/1: Then Koponey slipped his anchor an’ made a dinnyaiser for this lake.
1905		Sun. Times (Perth) 27 Aug. 4/8: Farewell, Perth, I must leave you. Going to do a Denny Hayeser back to the fields.

3. something large, outstanding, exceptional (depending on context).

1910		Sun. Times (Perth) 1 May 3rd sect. 17/8: The tom-tom film at Queen’s Hall is a dinnyhazer.
1912		Bulletin (Sydney) 8 Aug. Red Page/4: Dinnyhayser set lurk, lumping polony Kingpin’s straight monniker, chatting dead sudden stink Fogwards by long punt.
1988		McGill Dict. of Kiwi Sl. 37/1: dinnyhayser anything first-rate; eg ‘So that’s your new yacht. She’s a dinnyhayser, boy.’ From Australian boxer Dinny Hayes.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].