/ Dictionary / Index U USMS: Meaning and Definition of Find definitions for: USMS Pronunciation: [key] United States Maritime Service. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. USMC USN Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language