What does the word "Australia" mean?

The name Australia is derived from the Latin Terra Australis, and it means unknown southern land. It is a name used for putative lands in the southern hemisphere of the world; and thus, it is a name that was used accordingly from the time of the ancient Roman Empire.

The earliest recorded use of the word Australia in English was in 1625 in "A note of Australia del Espíritu Santo, written by Sir Richard Hakluyt" and published by Samuel Purchas in Hakluytus Posthumus, a corruption of the original Spanish name "Austrialia del Espíritu Santo" (Southern Land of the Holy Spirit, an island in Vanuatu).

The first time that the name Australia appears to have been officially used was in a despatch to Lord Bathurst. On April 4, 1817, Governor Lachlan Macquarie then acknowledges the receipt of Matthew Flinders' charts of Australia. On December 12, 1817, Macquarie recommended to the Colonial Office that the name be formally adopted. In 1824, the Admiralty agreed that the continent should be known officially as Australia.