Emperor Em"per*or, n. [OF. empereor, empereour, F. empereur, L. imperator, fr. imperare to command; in in + parare to prepare, order. See Parade, and cf. Imperative, Empress.] 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. Emperor goose (Zo["o]l.), a large and handsome goose (Philacte canagica), found in Alaska. Emperor moth (Zo["o]l.), one of several large and beautiful bombycid moths, with transparent spots on the wings; as the American Cecropia moth (Platysamia cecropia), and the European species (Saturnia pavonia). Emperor paper. See under Paper. Purple emperor (Zo["o]l.), a large, strong British butterfly (Apatura iris).