Byzantine

Concise Oxford English Dictionary © 2008 Oxford University Press:
Byzantine /bɪˈzantʌɪn, bʌɪ-/

▶adjective

• 1 relating to Byzantium (later called Constantinople, now Istanbul), the Byzantine Empire, or the Eastern Orthodox Church.

  ■ of a rich and highly decorated artistic and architectural style which developed in the Byzantine Empire and spread to Italy, Russia, and elsewhere.

• 2 excessively complicated and detailed.

  ■ characterized by deviousness or underhand methods.

▶noun a citizen of Byzantium or the Byzantine Empire.

– derivatives
Byzantinism /bɪˈzantɪnɪz(ə)m, bʌɪ-/ noun,
Byzantinist noun.