/ Dictionary / Index V Valentinian III: Meaning and Definition of Find definitions for: Valentinian III Pronunciation: [key] a.d.419?–455, emperor of the Western Roman Empire 425–455. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Valentinian II valentinite Related Content Daily Word Quiz: slough Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language