/ Dictionary / Index D Diocletian: Meaning and Definition of Find definitions for: Di•o•cle•tian Pronunciation: (dī"u-klē'shun), [key] — n. a.d. 245–316, Illyrian soldier: emperor of Rome 284–305. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: diocletian (Thesaurus) diocese Diocletian window Related Content Daily Word Quiz: reclusive Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language