Byzantium Byzantium /bəˈzæntiːəm/

noun

1. A continuation of the Roman Empire in the Middle East after its division in 395  ( Byzantine Empire , Byzantium , Eastern Roman Empire )
   a continuation of the Roman Empire in the Middle East after its division in 395
   
2. An ancient city on the Bosporus founded by the Greeks; site of modern Istanbul; in 330 Constantine I rebuilt the city and called it Constantinople and made it his capital  ( Byzantium )
   an ancient city on the Bosporus founded by the Greeks; site of modern Istanbul; in 330 Constantine I rebuilt the city and called it Constantinople and made it his capital