The Collaborative International Dictionary of English v.0.48:

Dichromatic \Di`chro*mat"ic\, a. [Pref. di- + chromatic: cf. Gr.
   ?.]
   1. Having or exhibiting two colors.
      [1913 Webster]

   2. (Zool.) Having two color varieties, or two phases
      differing in color, independently of age or sex, as in
      certain birds and insects.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dichromatic
    adj 1: of or relating to dichromatism
    2: having two colors; "a bicolor flower"; "a bicolored postage
       stamp" [syn: bicolor, bicolour, bicolored,
       bicoloured, bichrome, dichromatic]