/ Dictionary / Index M M.S.S.E.: Meaning and Definition of Find definitions for: M.S.S.E. Pronunciation: [key] Master of Science in Sanitary Engineering. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. M.S.Sc. MST Related Content Daily Word Quiz: resilient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language