The Collaborative International Dictionary
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).
Wikipedia
The Small Emperor Moth (Saturnia pavonia) is a moth of the family Saturniidae. Sometimes, the incorrect genus name Pavonia is still used for this species. This moth occurs throughout the Palearctic region and is the only member of its family to be found in the British Isles, where it is usually called simply the Emperor Moth.