/ Dictionary / Index M Mare Crisium: Meaning and Definition of Find definitions for: Ma•re Cri•si•um Pronunciation: (mär'ā krē'sē-um, mâr'ē), [key] (Sea of Crises) a dark plain in the first quadrant of the face of the moon: about 66,000 sq. mi. (170,000 sq. km). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. mare clausum Mare Erythraeum Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language