Source : Webster's Revised Unabridged Dictionary (1913)

Protean \Pro"te*an\, a.
   1. Of or pertaining to Proteus; characteristic of Proteus. ``
      Protean transformations.'' --Cudworth.

   2. Exceedingly variable; readily assuming different shapes or
      forms; as, an am[oe]ba is a protean animalcule.

Source : WordNet®

protean
     adj : taking on different forms; "eyes...of that baffling protean
           gray which is never twice the same"