Source : Webster's Revised Unabridged Dictionary (1913)

Achromic \A*chro"mic\, a. [Gr. ? colorless; ? priv. + ? color.]
   Free from color; colorless; as, in Physiol. Chem., the
   achromic point of a starch solution acted upon by an
   amylolytic enzyme is the point at which it fails to give any
   color with iodine.

Source : WordNet®

achromic
     adj : having no color [syn: {achromous}]