/ Dictionary / Index M MOS: Meaning and Definition of Find definitions for: MOS Pronunciation: [key] metal oxide semiconductor. mos. Pronunciation: [key] months. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mos (Thesaurus) morula mosaic Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language