Chalcedon has 3 different meanings across 2 categories:
Noun · Proper Noun
a former town on the Bosporus (now part of Istanbul); site of the Council of Chalcedon
the fourth ecumenical council in 451 which defined the two natures (human and divine) of Christ
An ancient maritime town of Bithynia, in Asia Minor in modern Turkey, almost directly opposite Byzantium.