/ Dictionary / Index T Theodosius I: Meaning and Definition of Find definitions for: The•o•do•si•us I Pronunciation: (thē"u-dō'shē-us, -shus), [key] (“the Great”)a.d. 346?–395, Roman emperor of the Eastern Roman Empire 379–395. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Theodosian Theodosius II Related Content Daily Word Quiz: abdicate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language