(of behaviour) acceptable - Australian & New Zealand – informal
As a noun dinkum, recorded from the late 19th century. was an English dialect word meaning hard work, honest toil. It now mainly features as an adjective in various Australian and New Zealand expressions.
RELATED IDIOMS :
fair and square
with absolute accuracy.
honestly and straightforwardly
a fair crack of the whip
a chance to participate or compete on equal terms - British informal
1989 - T. M. Albert - Tales of the Ulster Detective – You might think that the police concocted the circumstances to deny these men a fair crack of the whip.
a fair deal
used to request just treatment or to accept that it has been given - British informal
a fair field and no favour
equal conditions in a contest
fair play to someone
used as an expression of approval when someone has done something praiseworthy or the
right thing under the circumstances
used to request just treatment or assert that an arrangement is just – informal
2000 - Sallee Vickers - Miss Garnet's Angel Jonah - the wandering prophet, reminded her too much of her father. ‘He was a bit of a misery, wasn't he?’ But then, fair’s fair, living in the belly of a whale must give one a different point of view.
completely and finally - US informal
1997 - John Barth - The Sot-Weed Factor - And when the matter of hostages arose, the mother had said ’Pray God they will take Harry, for then we’d be quit of him for fair and not a penny poorer.’
it is a fair cop
an admission that the speaker has been caught doing wrong and deserves punishment
unfair (often used in or as a petulant protestation) - North American informal