/ Dictionary / Index M MS DOS: Meaning and Definition of Find definitions for: MS DOS Pronunciation: (em'es" dôs', -dos'), [key] — Trademark. Trademark. a microcomputer operating system. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. M.S.Dent. M.S.E. Related Content Daily Word Quiz: sinister Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language