\Arch`duke"\, n. [Pref. arch- + duke.]
A prince of the imperial family of Austria.

Note: Formerly this title was assumed by the rulers of
      Lorraine, Brabant, Austria, etc. It is now appropriated
      to the descendants of the imperial family of Austria
      through the make line, all such male descendants being
      styled archduke, and all such female descendants
      archduchesses.