The Collaborative International Dictionary of English v.0.48:

Argus \Ar"gus\, prop. n. [L. Argus, Gr. ?.]
   1. (Myth.) A fabulous being of antiquity, said to have had a
      hundred eyes, who has placed by Juno to guard Io. His eyes
      were transplanted to the peacock's tail.
      [1913 Webster]

   2. One very vigilant; a guardian always watchful.
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   3. (Zool.) A genus of East Indian pheasants. The common
      species (Argus giganteus) is remarkable for the great
      length and beauty of the wing and tail feathers of the
      male. The species Argus Grayi inhabits Borneo.
      [1913 Webster]