Vespasian Syllabification: (Ves·pa·sian)Pronunciation: /vesˈpāZHən/Definition of Vespasian ( ad 9-79), Roman emperor 69-79 and founder of the Flavian dynasty; Latin name Titus Flavius Vespasianus. His reign saw the restoration of financial and military order and the initiation of a public building program. Vespasian in other Oxford dictionaries Definition of Vespasian in the British & World English dictionary