/ Dictionary / Index M most significant digit: Meaning and Definition of Find definitions for: most' signif'icant dig'it Pronunciation: [key] the digit farthest to the left in a number. Abbr.: MSD Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Most Reverend most wanted list Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language