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.

ancient Greek settlement in Thrace on the European side of the Bosphorus, said to be named for its 7c. B.C.E. founder, Byzas of Megara. A place of little consequence until 330 C.E., when Constantine the Great re-founded it and made it his capital (see Constantinople).