The Collaborative International Dictionary of English v.0.48:

Mustang \Mus"tang\, n. [Sp. muste[~n]o belonging to the
   graziers, strayed, wild.] (Zool.)
   The half-wild horse of the plains in Mexico, California, etc.
   It is small, hardy, and easily sustained.
   [1913 Webster]

   Mustard grape (Bot.), a species of grape (Vitis
      candicans), native in Arkansas and Texas. The berries are
      small, light-colored, with an acid skin and a sweet pulp.
      [1913 Webster]