Australasia comprises Australia, New Zealand, and some neighbouring islands. It is used in a number of different contexts including geopolitically, physiogeographically, and ecologically where the term covers several slightly different but related regions.coined the term in Histoire des navigations aux terres australes. He derived it from the Latin for "south of Asia" and differentiated the area from Polynesia and the southeast Pacific.
In Australia, "Australasia" is considered to be Australia, New Zealand, New Guinea, and the neighbouring islands of the Pacific.
In New Zealand, it means Australia, New Zealand and former New Zealand dependencies.
Two Merriam-Webster dictionaries online define Australasia as "Australia, New Zealand, and Melanesia". The American Heritage Dictionary online recognizes two senses in use: one more precise, being similar to the aforementioned senses, and the other broader, loosely covering all of Oceania.