The Collaborative International Dictionary of English v.0.48:

Polychromatic \Pol`y*chro*mat"ic\, a. [Poly- + chromatic.]
   Showing a variety, or a change, of colors.
   [1913 Webster]

   Polychromatic acid (Old Chem.), a substance obtained by the
      action of nitric acid on aloes.
      [1913 Webster]