Green’s Dictionary of Slang

(Aus./N.Z.) an all-purpose Aus. term of approbation.

1943		Argus (Melbourne) 26 June 7/3: When your hostess suddenly remmbers [...] to ask if you are having a good time, ‘Beaut!’ you sat brightly.
1960		‘Nino Culotta’ Cop This Lot 189: ‘You have had a good time in Germany, Dennis?’ ‘Beaut Max.’.
1963–74		B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 16: Jeez, no . . . I mean beaut.
1971		F. Hardy Outcasts of Foolgarah 89: Beaut, Florrie, you always were handy with the pen.
1985		B. Dickins What the Dickins 140: You check the lamb; done to a turn. Cut off a bit. Beaut, beaut. It’s ready now.
1991		T. Winton Cloudstreet 287: Rose felt her cheeks glowing. Beaut!
1992		K. Lette Llama Parlour 9: Apart from that, everything was fine, beaut, no wuckin’ furries, as we say back home.