/ Dictionary / Index M MSG: Meaning and Definition of Find definitions for: MSG Pronunciation: [key] See msg. Pronunciation: [key] message. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: msg (Thesaurus) M.S.For. M.S.Geol.E. Related Content Daily Word Quiz: dissonant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language