(n.) The sovereign or supreme monarch of an empire; -- a title of dignity superior to that of king; as, the emperor of Germany or of Austria; the emperor or Czar of Russia.

anointed king chief chieftain crowned head dynast grand duke high chief imperator king king-emperor kinglet lord paramount majesty monarch overlord paramount petty king potentate prince prince consort royal royal personage royalty ruler sovereign suzerain tetrarch