Source : Webster's Revised Unabridged Dictionary (1913)

Bandog \Ban"dog`\, n. [Band + dog, i.e., bound dog.]
   A mastiff or other large and fierce dog, usually kept chained
   or tied up.

         The keeper entered leading his bandog, a large
         bloodhound, tied in a leam, or band, from which he
         takes his name.                          --Sir W.
                                                  Scott.