The Aussie slang dictionary - Frank Povah

Australian English has always been rich in slang and dialect words, many of which
dinkum for example
came out from Great Britain with the convicts and their meanings and pronunciation changed. Words from Indigenous languages, such as boomerang, began to be adopted and modified almost from the very first
and English words and phrases such as dead-finish were taken into Aboriginal languages, modified and loaned back to the English speakers. As time went by, words still in common use in Australia were no longer current in their country of origin, and so became Australianised.