Proteus

Part of speech: noun (n.)

1. A sea god in the service of Neptune who assumed different shapes at will. Hence, one who easily changes his appearance or principles.

2. 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.

3. A changeable protozoan; an amoeba.