Source : Webster's Revised Unabridged Dictionary (1913)

Proteus \Pro"te*us\, n. [L., Gr. ?.]
   1. (Class. Myth.) A sea god in the service of Neptune who
      assumed different shapes at will. Hence, one who easily
      changes his appearance or principles.

   2. (Zo["o]l.)
      (a) A genus of aquatic eel-shaped amphibians found in
          caves in Austria. They have permanent external gills
          as well as lungs. The eyes are small and the legs are
          weak.
      (b) A changeable protozoan; an am[oe]ba.

Source : WordNet®

Proteus
     n 1: (Greek mythology) a prophetic god who served Poseidon; was
          capable of changing his shape at will
     2: type genus of the Proteidae [syn: {genus Proteus}]

Source : Free On-Line Dictionary of Computing

PROTEUS
     
        An extensible language, the core of {PARSEC}.
     
        ["The Design of a Minimal Expandable Computer Language",
        J.R. Bell, PhD Thesis, CS, {Stanford University} (Dec 1968)].