/ Dictionary / Index M Mare Chronium: Meaning and Definition of Find definitions for: Ma're Chro'ni•um Pronunciation: (krō'nē-um), [key] an area in the southern hemisphere of Mars, appearing as a dark region when viewed telescopically from the earth. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Mare Boreum Mare Cimmerium Related Content Daily Word Quiz: tactful Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language