armgaunt

from The Collaborative International Dictionary of English v.0.48

Armgaunt \Arm"gaunt`\, a.
   With gaunt or slender legs. (?) "An armgaunt steed." --Shak.
   [1913 Webster]

   Note: This word is peculiar to Shakespeare. Its meaning has
         not yet been satisfactorily explained.
         [1913 Webster]