Green’s Dictionary of Slang

(usu. Aus.) honestly! really! on the level!

1887		Riverine Grazier (NSW) 24 May 2/7: When Friend Hills took the secretaryship of the Hay Jockey Club I [...] prophesied straight away— fair dinkum— that Hills would do it, and he has done it.
1894		Bulletin (Sydney) 5 May 13/3: ‘And did yer stouch him back?’ ‘No.’ [...] ‘Fair dinkum?’ ‘Yes.’.
1897		Barrier Miner (Broken Hill, NSW) 27 May3/1: ‘You’ve learnt some Australian slang, too!’ [...] ‘I know “fair dinkum,” “lor blime,” and a few other bits.
1901		Bulletin (Sydney) 14 Dec. 15/4: Your real name is Gawd; now, straight dinkum, ain’t it?
1906		E. Dyson Fact’ry ’Ands 64: ‘Meanin’?’ he pointed to the centre of his breast, and his eyes were round with inquiry. ‘Fair dinkum,’ telegraphed Linda. [Ibid.] 119: Fair dink, I wouldn’ be surprised iv ’is jills reaped off his tangled web iv whiskers.
1911		L. Stone Jonah 106: ‘Fair dinkum?’ cried Chook. Pinkey nodded her head.
1914		Sport (Adelaide) 25 Sept. 5/7: Soon going to do the trick, Jack [...] square dink.
1916		C.J. Dennis ‘The Push’ in Moods of Ginger Mick 41: An’ they’re drillin’ ’ere together, men uv ev’ry creed an’ kind. / It’s Australia! Solid! Dinkum! that ’as left the land be’ind.
1917		W. Muir Observations of Orderly 222: I could see he knew I’d clicked a packet, square dinkum, this trip.
1919		E. Dyson ‘Out of Khaki’ in ‘Hello, Soldier!’ 99: Fair dink, I loved the uniform!
1919		C.H. Thorp Handful of Ausseys 174: Fair dinkum, that cove [...] fair reminded me uv a calf we ’ad once.
1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words 268: Square Dinkum: True. Straightforward. Correct.
1932		‘William Hatfield’ Ginger Murdoch 259: But dinkum! You’re the prettiest girl about these parts, know that?
1938		X. Herbert Capricornia (1939) 132: Now come on Cho, or I’ll makim big-feller trouble. Fair dinkum.
1941		N.Y. Herald Trib. 29 June 9/2: ‘Fair dinkum’ is the traditional Australian equivalent to bona fide or ‘honest injun’.
1959		(con. WWII) B. Cochrell Barren Beaches of Hell 41: ‘Fair dinkum,’ Chick said.
1964		N.B. Harvey Any Old Dollars, Mister? 75: ‘Crikey. That’s awful.’ ‘Dinkum,’ he said, and nodded.
1965		W. Dick Bunch of Ratbags 186: ‘Fair dinkum?’ said Ritchie. ‘Or are yuh bull-dustin’?’.
1973		(con. 1930s) F. Huelin ‘Keep Moving’ 28: ‘He’s the JP who sentenced us,’ ‘Dinkum!’.
1976		D. Ireland Glass Canoe (1982) 54: ‘A hundred? You kidding?’ asked the barmaid. ‘Fair dinkum,’ we said solemnly.
1986		R. Beckett Dinkum Aussie Dict. 19: Dinkum: Absolutely authentic as in the expression, ‘Fair dinkum mate, I wouldn’t lie to you now would I?’.
1992		R.G. Barrett Davo’s Little Something 8: Fair dinkum, I feel sorry for you.
1993		M.B. ‘Chopper’ Read How to Shoot Friends 23: Fair dinkum, compared with some of these prison officers, I could have been a Rhodes scholar.
2001		K. Sampson Outlaws (ms.) 141: Fair dinkum, some of the Wolvo posse did help set this up.
2011		ntnews.com.au 21 Mar. 🌐 Fair dinkum, mate. Next time don’t f*** with the poofters.
2012		(con. 1943) G.S. Manson Irish Fandango [ebook] ‘[F]air dink [...] He went after a lost football at training last night and fell into Kedron Brook’.
2018		R. O’Neill ‘Ocker’ in The Drover’s Wives (2019) 182: ‘I’ll sure as hell never go bloody drovin’ [...] Fair dinkum!’.