Julian2 Syllabification: (Jul·ian)Pronunciation: /ˈjo͞olyən/Definition of Julian (circa ad 331–363), Roman emperor 360–363; nephew of Constantine; full name Flavius Claudius Julianus; known as the Apostate. He restored paganism as the state cult in place of Christianity, but this was reversed after his death. Julian in other Oxford dictionaries Definition of Julian in the British & World English dictionary