/ Dictionary / Index U Utopia Planitia: Meaning and Definition of Find definitions for: Uto'pia Pla•ni'tia Pronunciation: (plu-nē'shu), [key] a plain in the northern hemisphere of Mars that was the landing site of the Viking II space probe on September 3, 1976. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. utopian socialism utopism Related Content Daily Word Quiz: menagerie Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language