Australasia comprises Australia, New Zealand, and some neighbouring islands (see the section Derivation and definitions). It is used in a number of different contexts including geopolitically, physiogeographically, and ecologically where the term covers several slightly different but related regions.
Charles de Brosses coined the term (as French Australasie) 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).
In New Zealand, it means Australia, New Zealand and former New Zealand dependencies.
Two Merriam-Webster dictionaries online (Collegiate and Unabridged) 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.