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: Webster's Revised Unabridged Dictionary (1913)