The name "Australia" comes from the Latin phrase Terra Australis Incognita, which translates to "unknown southern land." This term was used by ancient cartographers to describe a hypothetical continent believed to exist in the Southern Hemisphere. While the name was widely used for centuries to denote the general idea of a southern landmass, it did not initially refer to the landmass we now know as Australia.

In the 17th century, Dutch explorers began mapping the continent, referring to it as "New Holland." The name "Australia" was first popularized by British explorer Matthew Flinders, who circumnavigated the continent in 1803. Despite his efforts, the name Terra Australis continued to appear in his published account in 1814.

It was not until 1817 that New South Wales Governor Lachlan Macquarie formally recommended the name "Australia" to replace "New Holland." The British Admiralty officially adopted the name in 1824, and it was included in British legislative acts by 1828. The name "Australia" gained further legitimacy with its inclusion in The Australia Directory published by the United Kingdom Hydrographic Office in 1830.

The term "Commonwealth of Australia" was officially established when the Commonwealth of Australia Constitution Act was passed by the UK Parliament in 1900, formalizing the name of the newly federated nation.

Over time, colloquial terms for the country have emerged, including "Oz," "Straya," and "Down Under," reflecting the country's unique cultural identity and informal style.