Source : Webster's Revised Unabridged Dictionary (1913)

Leghorn \Leg"horn\ (-h[^o]rn), n.
   A straw plaiting used for bonnets and hats, made from the
   straw of a particular kind of wheat, grown for the purpose in
   Tuscany, Italy; -- so called from Leghorn, the place of
   exportation.

Source : WordNet®

leghorn
     n : a stiff straw hat with a flat crown [syn: {boater}, {Panama},
          {Panama hat}, {sailor}, {skimmer}, {straw hat}]