The Collaborative International Dictionary of English v.0.48:

Roan \Roan\ (r[=o]n), 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.
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            Give my roan a drench.                --Shak.
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   2. Made of the leather called roan; as, roan binding.
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   Roan antelope (Zool.), 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.
      [1913 Webster]