supreme power; sovereignty; sway; dominion.-the dominion of an emperor; the territory or countries under the jurisdiction and dominion of an emperor (rarely of a king), usually of greater extent than a kingdom, always comprising a variety in the nationality of, or the forms of administration in, constituent and subordinate portions; as, the austrian empire.-any dominion; supreme control; governing influence; rule; sway; as, the empire of mind or of reason.