Achromatizing

from The Collaborative International Dictionary of English v.0.48

Achromatize \A*chro"ma*tize\, v. t. [imp. & p. p.
   {Achromatized}; p. pr. & vb. n. {Achromatizing}.] [Gr. 'a
   priv. + ? color.]
   To deprive of color; to make achromatic. [Also spelled
   {achromatise}.]
   [1913 Webster]