/ Dictionary / Index M missing mass: Meaning and Definition of Find definitions for: miss'ing mass' Pronunciation: [key] the difference in mass in the universe between that observed to exist and that necessary for the closed universe model. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. missing link missiology Related Content Daily Word Quiz: soporific Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language