Synonyms for Dichromatism (same or very similar meaning)
WordNet sense 1 (a deficiency of color vision in which the person can match any given hue by mixing only two other wavelengths of light (as opposed to the three wavelengths needed by people with normal color vision)):
dichromacy, dichromasy, dichromatopsia, dichromiaFrom the ODE community, based on WordNetadd/edit