Source : Webster's Revised Unabridged Dictionary (1913)

Koulan \Kou"lan\, n. [Native name.] (Zo["o]l.)
   A wild horse ({Equus, or Asinus, onager}) inhabiting the
   plants of Central Asia; -- called also {gour}, {khur}, and
   {onager}. [Written also {kulan}.]

   Note: It is sometimes confounded with the dziggetai, to which
         it is closely related. It is gray in winter, but
         fulvous in summer. It has a well defined, dark, dorsal
         stripe, and a short, erect mane. In size, it is
         intermediate between the horse and ass.