Source : Webster's Revised Unabridged Dictionary (1913)

Spread \Spread\,
   imp. & p. p. of {Spread}, v.

   {Spread eagle}.
   (a) An eagle with outspread wings, the national emblem of the
       United States.
   (b) The figure of an eagle, with its wings elevated and its
       legs extended; often met as a device upon military
       ornaments, and the like.
   (c) (Her.) An eagle displayed; an eagle with the wings and
       legs extended on each side of the body, as in the
       double-headed eagle of Austria and Russia. See
       {Displayed}, 2.

Source : WordNet®

spread eagle
     n 1: an emblem (an eagle with wings and legs spread) on the
          obverse of the Great Seal of the United States
     2: a skating figure executed with the skates heel to heel in a
        straight line