Oceania is a major geographical region of the planet Earth, mostly in the southern hemisphere, consisting of Australasia (the Australian continent and New Zealand), Micronesia, Melanesia and Polynesia. It is so named because it covers the lands scattered across the Pacific Ocean, that are not part of Asia and are not part of the Americas.
Definitions of the exact borders vary.
In the novel 1984 by George Orwell, "Oceania" is one of the three global superpowers. Its territory consists, approximately, of the former British Empire plus North America.