/ Dictionary / Index L Leo III: Meaning and Definition of Find definitions for: Leo III Pronunciation: [key] a.d. c750–816, Italian ecclesiastic: pope 795–816. (“the Isaurian”), a.d. c680–741, Eastern Roman emperor 717–741. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Leo II Leo IV Related Content Daily Word Quiz: penchant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language