The Collaborative International Dictionary of English v.0.48:

Roc \Roc\, n. [Ar. & Per. rokh or rukh. Cf. Rook a castle.]
   A monstrous bird of Arabian mythology. [Written also rock,
   and rukh.] --Brande & C.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rukh \Rukh\, n. [Srr Roc.]
   1. The roc.
      [1913 Webster]

   2. (Zool.) A large bird, supposed by some to be the same as
      the extinct Epiornis of Madagascar. [Obs.]
      [1913 Webster]