(circa 346–95), Roman emperor 379–95; full name Flavius Theodosius; known as Theodosius the Great. Proclaimed joint emperor by the Emperor Gratian in 379, he took control of the Eastern Empire and ended the war with the Visigoths. A pious Christian, in 391 he banned all forms of pagan worship.
Theodosius I in other Oxford dictionaries
Definition of Theodosius I in the US English dictionary