The Collaborative International Dictionary of English v.0.48:

Empire \Em"pire\, n. [F., fr. L. imperium a command,
   sovereignty, dominion, empire, fr. imperare. See Emperor;
   cf. Imperial.]
   1. Supreme power; sovereignty; sway; dominion. "The empire of
      the sea." --Shak.
      [1913 Webster]

            Over hell extend
            His empire, and with iron scepter rule. --Milton.
      [1913 Webster]

   2. 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.
      [1913 Webster]

            Empire carries with it the idea of a vast and
            complicated government.               --C. J. Smith.
      [1913 Webster]

   3. Any dominion; supreme control; governing influence; rule;
      sway; as, the empire of mind or of reason. "Under the
      empire of facts." --M. Arnold.
      [1913 Webster]

            Another force which, in the Middle Ages, shared with
            chivalry the empire over the minds of men. --A. W.
                                                  Ward.
      [1913 Webster]

   Celestial empire. See under Celestial.

   Empire City, a common designation of the city of New York.


   Empire State, a common designation of the State of New
      York.

   Syn: Sway; dominion; rule; control; reign; sovereignty;
        government; kingdom; realm; state.
        [1913 Webster]

WordNet (r) 3.0 (2006):

empire
    n 1: the domain ruled by an emperor or empress; the region over
         which imperial dominion is exercised [syn: empire,
         imperium]
    2: a group of countries under a single authority; "the British
       created a great empire"
    3: a monarchy with an emperor as head of state
    4: a group of diverse companies under common ownership and run
       as a single organization [syn: conglomerate, empire]
    5: an eating apple that somewhat resembles a McIntosh; used as
       both an eating and a cooking apple

The Free On-line Dictionary of Computing (19 January 2023):

empire

    Any of a family of military simulations derived from a
   game written by Peter Langston many years ago.  Five or six
   multi-player variants of varying degrees of sophistication
   exist, and one single-player version implemented for both
   Unix and VMS; the latter is even available as MS-DOS
   freeware.  All are notoriously addictive.

   [Jargon File]

   (1995-08-06)


The Jargon File (version 4.4.7, 29 Dec 2003):

empire
 n.

    Any of a family of military simulations derived from a game written by
    Peter Langston many years ago. A number of multi-player variants of varying
    degrees of sophistication exist, and one single-player version implemented
    for both Unix and VMS; the latter is even available as MS-DOS/Windows
    freeware. All are notoriously addictive. Of various commercial derivatives
    the best known is probably “Empire Deluxe” on PCs and Amigas.

    Modern empire is a real-time wargame played over the internet by up to 120
    players. Typical games last from 24 hours (blitz) to a couple of months
    (long term). The amount of sleep you can get while playing is a function of
    the rate at which updates occur and the number of co-rulers of your
    country. Empire server software is available for Unix-like machines, and
    clients for Unix and other platforms. A comprehensive history of the game
    is available at http://www.empire.cx/infopages/History.html. The Empire
    resource site is at http://www.empire.cx/.