Origin: "Australia"

The name Australia derives from Latin "australis" meaning "southern", and dates back to 2nd century legends of an "unknown southern land" (that is terra australis incognita). The explorer Matthew Flinders named the land Terra Australis, which was later abbreviated to the current form. Previously, when the Dutch explored the area they named it Nova Hollandicus or New Holland.

Flinders later renamed the land Australia in a chart compiled in 1804 whilst he was held prisoner by the French in Mauritius. When he returned to England and published his works in 1814 he was forced to change the name to Terra Australis by the British Admiralty. Governor Macquarie of New South Wales became aware of Flinders' preference for the name Australia and used it in his dispatches to England. In 1824 the British Admiralty finally accepted that the continent should be known officially as Australia.

Source: http://www.sheppardsoftware.com/Oceaniaweb/factfile/Unique-facts-Oceania2.htm