Green’s Dictionary of Slang

1. hoorah! hooray!

1880		Hartlepool Northern Dly Mail 25 Nov. 3/6: Lord E. was showy. He had a good deal of the quack about him. So much for Lord Ellenborough hooroo! (Polish him off — hurroo!).
1898		F.P. Dunne Mr Dooley in Peace and War 154: Take an ax, an ax, an ax to thim. Hooroo, hooroo, hellabaloo. Christian Bro-others!
1900		Sporting Times 24 Mar. 1/1: Begad and hooroo! So the consideration of water had to be adjourned to let Irishmen talk. Why didn’t you put a little whisky in the water, Stuart? Is there no Irish Stew-art about you?
1905		Sporting Times 18 Feb. 1/1: There’ll be lots of hooroo, and be jabers, shillelaghs in the air and wigs on the green over this job.
1937		A.W. Upfield Murder Down Under (1951) 29: Hooroo! Saved – I’m saved!
1951		Cusack & James Come in Spinner (1960) 265: Kim was greeted with loud hooroos.

2. (Aus., also aroo! hurray! hurroo!) goodbye.

1919		C.H. Thorp Handful of Ausseys 271: He sauntered off amid a jovial chorus of ‘Goodbyes’ and ‘Hooray, cobber, see you again’.
1931		‘William Hatfield’ Sheepmates 240: ‘Well, hooroo!’ And he was gone.
1941		Baker Popular Dict. Aus. Sl.
1949		L. Glassop Lucky Palmer 103: I won twenty, just going easy, and I’m getting out before I lose it. Hooroo, ‘Lucky’. Hooroo, Max.
1957		D. Niland Call Me When the Cross Turns Over (1958) 99: Barbie said, ‘hooroo’.
1965		F.J. Hardy Yarns of Billy Borker 94: Whew, look at the time. I’ve got to be going. Hooroo.
1969		L. Hadow Full Cycle 249: ‘Hurroo,’ he said, and [...] hurried off down the road.
1973		(con. 1940s–60s) Hogbotel & ffuckes ‘Pull me Dungarees Down’ in Snatches and Lays 54: I’ll have to say hooroo, Blue.
1986		R. Beckett Dinkum Aussie Dict. 30: Hooroo: Literally goodbye, as in, ‘Well hooroo then, I’ll catch yer later.’.
1996		Penguin Bk of More Aus. Jokes 427: A farmer was standing on the verandah farewelling a couple of visitors. When they were about 30 metres away he called out, ‘Oo’roo’. The couple turned, waved and called, ‘Oo’roo’ back.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].
2022		in D. Andrew Aussie Sl.