WordNet (r) 3.0 (2006):

Constantine I
    n 1: Emperor of Rome who stopped the persecution of Christians
         and in 324 made Christianity the official religion of the
         Roman Empire; in 330 he moved his capital from Rome to
         Byzantium and renamed it Constantinople (280-337) [syn:
         Constantine, Constantine I, Constantine the Great,
         Flavius Valerius Constantinus]