Australasia is a region of Oceania comprising Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. The term was coined by Charles de Brosses in Histoire des navigations aux terres australes (1756). He derived it from the Latin for "south of Asia" and differentiated the area from Polynesia (to the east) and the southeast Pacific (Magellanica). It is also distinct from Micronesia (to the northeast). Australasia sits on the Indo-Australian Plate, together with India.
Human geography 
Geopolitically, Australasia is sometimes used as a term for Australia and New Zealand together in the absence of another word limited to those two countries. Sometimes the island of New Guinea (Papua New Guinea and the Indonesian part of the island) is encompassed by the term. There are many organisations whose names are prefixed with "(Royal) Australasian Society" that are limited to just Australia and New Zealand.
In the past, Australasia has been used as a name for combined Australia/New Zealand sporting teams. Examples include tennis between 1905 and 1915, when New Zealand and Australia combined to compete in the Davis Cup international tournament, and at the Olympic Games of 1908 and 1912.
Ecological geography 
From an ecological perspective the Australasia ecozone is a distinct region with a common geologic and evolutionary history and a great many unique flora and fauna. In this context, Australasia is limited to Australia, New Guinea, New Zealand, New Caledonia, and neighbouring islands, including the Indonesian islands from Lombok and Sulawesi eastward. The biological dividing line from the Indomalaya ecozone of tropical Asia is the Wallace Line – Borneo and Bali lie on the western, Asian side.
Australia, New Zealand and New Caledonia are all fragments of the ancient supercontinent Gondwana, the marks of which are still visible in the Christmas Island Seamount Province and other geophysical entities. These three land masses have been separated from other continents, and from one another, for millions of years. All of Australasia shares the Antarctic flora, although the northern, tropical islands also share many plants with Southeast Asia.
Australia, New Guinea, and Tasmania are separated from one another by shallow continental shelves, and were linked together when the sea level was lower during the Ice Ages. They share a similar fauna which includes marsupial and monotreme mammals and ratite birds. Eucalypts are the predominant trees in much of Australia and New Guinea. New Zealand has no native land mammals, but also had ratite birds, including the kiwi and the extinct moa. The Australasia ecozone includes some nearby island groups, like Wallacea, the Bismarck Archipelago, Solomon Islands, and Vanuatu, which were not formerly part of Gondwana, but which share many characteristic plants and animals with Australasia.
See also 
- Richards, Kel (2006). "Australasia". Wordwatch. ABC News Radio. Retrieved 2006-09-30.
- Australasia Encyclopædia Britannica Eleventh Edition
Media related to Australasia at Wikimedia Commons