The name Australia is derived from the Latin australis, meaning "southern". The country has been referred to colloquially as Oz since the early 20th century. Aussie is a common colloquial term for "Australian". In neighbouring New Zealand the term "Aussie" is sometimes applied as a noun to the nation as well as its residents.
Legends of Terra Australis Incognita—an "unknown land of the South"—date back to Roman times and were commonplace in medieval geography, although not based on any documented knowledge of the continent. Following European discovery, names for the Australian landmass were often references to the famed Terra Australis.
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", published by Samuel Purchas in Hakluytus Posthumus, a corruption of the original Spanish name "Tierra Austral del Espíritu Santo" (Southern Land of the Holy Spirit) for an island in Vanuatu. The Dutch adjectival form Australische was used in a Dutch book in Batavia (Jakarta) in 1638, to refer to the newly discovered lands to the south. Australia was later used in a 1693 translation of Les Aventures de Jacques Sadeur dans la Découverte et le Voyage de la Terre Australe, a 1676 French novel by Gabriel de Foigny, under the pen-name Jacques Sadeur. Referring to the entire South Pacific region, Alexander Dalrymple used it in An Historical Collection of Voyages and Discoveries in the South Pacific Ocean in 1771. By the end of the 18th century, the name was being used to refer specifically to Australia, with the botanists George Shaw and Sir James Smith writing of "the vast island, or rather continent, of Australia, Australasia or New Holland" in their 1793 Zoology and Botany of New Holland, and James Wilson including it on a 1799 chart.
The name Australia was popularised by the explorer Matthew Flinders, who pushed for it to be formally adopted as early as 1804. When preparing his manuscript and charts for his 1814 A Voyage to Terra Australis, he was persuaded by his patron, Sir Joseph Banks, to use the term Terra Australis as this was the name most familiar to the public. Flinders did so, and published the following rationale:
There is no probability, that any other detached body of land, of nearly equal extent, will ever be found in a more southern latitude; the name Terra Australis will, therefore, remain descriptive of the geographical importance of this country, and of its situation on the globe: it has antiquity to recommend it; and, having no reference to either of the two claiming nations, appears to be less objectionable than any other which could have been selected.
In the footnote Flinders wrote:
This is the only occurrence of the word Australia in that text; but in Appendix III, Robert Brown's General remarks, geographical and systematical, on the botany of Terra Australis, Brown makes use of the adjectival form Australian throughout,—the first known use of that form. Despite popular conception, the book was not instrumental in the adoption of the name: the name came gradually to be accepted over the following ten years.
The first time that the name Australia appears to have been officially used was in a despatch to Lord Bathurst of 4 April 1817 in which Governor Lachlan Macquarie acknowledges the receipt of Capt. Flinders' charts of Australia. On 12 December 1817, Macquarie recommended to the Colonial Office that it be formally adopted. In 1824, the Admiralty agreed that the continent should be known officially as Australia.