Vitellius, Aulus Syllabification: (Vi·tel·li·us, Aulus)Pronunciation: /vəˈtelēəs/Definition of Vitellius, Aulus (15-69), Roman emperor. He was acclaimed emperor in January 69 by the legions in Germany during the civil wars that followed the death of Nero. He defeated Otho but was killed by the supporters of Vespasian. Vitellius, Aulus in other Oxford dictionaries Definition of Vitellius, Aulus in the British & World English dictionary