/ Dictionary / Index O Oahu: Meaning and Definition of Find definitions for: O•a•hu Pronunciation: (ō-ä'h), [key] — n. an island in central Hawaii: third largest and most important island of the state; location of Honolulu. 630,528; 589 sq. mi. (1525 sq. km). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: oahu (Thesaurus) oaf oak Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language