n. 1 the sovereign of an empire. 2 a sovereign of higher rank than a king. emperor moth a large moth, Saturnia pavonia, of the silk-moth family, with eye-spots on all four wings. emperor penguin the largest known penguin, Aptenodytes forsteri, of the Antarctic. emperorship n.
[ ME f. OF emperere, empereor f. L imperator -oris f. imperare command ]