a group of 15 small islands in the Pacific, E of the Philippines: divided into Guam, a possession of the U.S., and the North Marianas, formally under U.S. trusteeship. 453 sq. mi. (1127 sq. km).
a chain of coral and volcanic islands in Micronesia (including Guam and the Northern Marianas) halfway between New Guinea and Japan; discovered by Magellan in 1521 [syn: Mariana Islands]