Dinkum

This word, which today is principally Australian, first turns up in print in Australia in Robbery Under Arms (1888) by Ralph Boldrewood, “It took us an hour’s hard dinkum to get near the peak.” Thus, its first use means exertion or hard work. Within a few short years, however, by 1894 according to the OED, it was being used as an adjective meaning honest, genuine or real, which is pretty much its current meaning. The origin of the word remains unknown, but there is some evidence it may have derived from English dialect, as stated in English Dialect Dictionary (1896-1906) by Joseph Wright, who claims the expression fair dinkum meaning fair play was encountered in Lincolnshire. Most etymologists, however, including those at the OED, discount this English origin and it remains, for now, a uniquely antipodean expression.