Byzantium

from 330 C.E. to 1930 the name of what is now Istanbul and formerly was Byzantium, the city on the European side of the Bosphorus that served as the former capital of the Byzantine and Ottoman empires, from Greek Konstantinou polis "Constantine's city," named for Roman emperor Flavius Valerius Aurelius Constantinus (see Constantine), who transferred the Roman capital there.

gold coin issued by the emperors at Constantinople, c. 1200, from Old French besant (12c.), from Latin byzantius, short for Byzantius nummus "coin of Byzantium." They circulated widely in Europe in the early Middle Ages, when most countries had no gold coins of their own.

pertaining to Byzantium (q.v., original name of Constantinople, modern Istanbul), 1770, from Late Latin Byzantinus; originally used of the style of art and architecture developed there 4c.-5c. C.E.; later in reference to the complex, devious, and intriguing character of the royal court of Constantinople (1937). As a noun from 1770. Byzantian is from 1610s.