DINKUM

Colloquial words that come from nowhere can be redeployed and radically redesigned in different times and places. Dinkum is one such, which probably originated in C19 Northern English dialects, though in Australia it's sometimes thought to consist of two Chinese syllables. Citations in the Oxford English Dictionary Online show it was used among Sheffield coal-miners as a noun meaning "hard work", and in North Lincolnshire as an adjective in the sense of "honest, genuine".  Both senses were known in Australia by 1900, and they merge in the self-referential use of Dinkums by Australian soldiers (the "Diggers" of Second Division of the AIF in World War I), and for New Zealanders as well. Like many Australian colloquialisms, dinkum in its adjectival sense was subsequently abbreviated to dinky. But this same string of letters (dinky) was harnessed in American English in the 1980s as the acronym for the consumer label "dual income, no kids". It was widely applied to career-oriented, upwardly mobile adults for whom a work/lifestyle balance was not a high priority. Even more curiously, the acronym now appears in American sources as dinkum, standing for "dual income, no kids, unbelievable mortgage".  For Australians this puts hard grind back into the word – as the work they owe to the bank to pay the mortgage on the place they may not have much time to enjoy living in. Plus ça change...