Source : Webster's Revised Unabridged Dictionary (1913)

Roan \Roan\, n.
   1. The color of a roan horse; a roan color.

   2. A roan horse.

   3. A kind of leather used for slippers, bookbinding, etc.,
      made from sheepskin, tanned with sumac and colored to
      imitate ungrained morocco. --DeColange.

   {Roan tree}. (Bot.) See {Rowan tree}.

Roan \Roan\, a. [F. rouan; cf. Sp. roano, ruano, It. rovano,
   roano.]
   1. Having a bay, chestnut, brown, or black color, with gray
      or white thickly interspersed; -- said of a horse.

            Give my roan a drench.                --Shak.

   2. Made of the leather called roan; as, roan binding.

   {Roan antelope} (Zo["o]l.), a very large South African
      antelope ({Hippotragus equinus}). It has long sharp horns
      and a stiff bright brown mane. Called also {mahnya},
      {equine antelope}, and {bastard gemsbok}.

Source : WordNet®

roan
     adj : (used of especially horses) having a brownish coat thickly
           sprinkled with white or gray; "a roan horse"
     n 1: a soft sheepskin leather that is colored and finished to
          resemble morocco; used in bookbinding
     2: horse having a roan coat