/ Dictionary / Index M Mare Island: Meaning and Definition of Find definitions for: Mare' Is'land Pronunciation: (mâr), [key] an island in the N part of San Francisco Bay, California. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Mare Imbrium Marek's disease Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language