WordNet sense 1 (the largest city and former capital of Turkey; rebuilt on the site of ancient Byzantium by Constantine I in the fourth century; renamed Constantinople by Constantine who made it the capital of the Byzantine Empire; now the seat of the Eastern Orthodox Church):

Istanbul, Stamboul, Stambul

WordNet sense 2 (the council in 869 that condemned Photius who had become the patriarch of Constantinople without approval from the Vatican, thereby precipitating the schism between the eastern and western churches):

Fourth Council of Constantinople

WordNet sense 3 (the sixth ecumenical council in 680-681 which condemned Monothelitism by defining two wills in Christ, divine and human):

Third Council of Constantinople

WordNet sense 4 (the fifth ecumenical council in 553 which held Origen's writings to be heretic):

Second Council of Constantinople

WordNet sense 5 (the second ecumenical council in 381 which added wording about the Holy Spirit to the Nicene Creed):

First Council of Constantinople