An ancient Greek city, founded in the 7th century BC, at the southern end of the Bosporus, site of the modern city of Istanbul. It was rebuilt by Constantine the Great in AD 324–30 as Constantinople.
Definition of Byzantium in US English:
Byzantium
proper noun
An ancient Greek city, founded in the 7th century BC, at the southern end of the Bosporus, site of the modern city of Istanbul. It was rebuilt by Constantine the Great in AD 324–330 as Constantinople.