one of the three major divisions of the Pacific islands, south of the equator and including groups from the Bismarck Archipelago to the Fiji Islands
See Melanesia in American Heritage Dictionary 4
(mĕlˌə-nēˈzhə, -shə)
A division of Oceania in the southwest Pacific Ocean comprising the islands northeast of Australia and south of the equator. It includes the Solomon Islands, Vanuatu, New Caledonia, the Bismarck Archipelago, various other island groups, and sometimes New Guinea.