dichromacy, dichromasy, dichromatism, dichromatopsia, dichromia - 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)

monochromacy, monochromasy, monochromatic vision, monochromatism, monochromia - complete color blindness; colors can be differentiated only on the basis of brightness

birth defect, congenital abnormality, congenital anomaly, congenital defect, congenital disorder - a defect that is present at birth

vision defect, visual defect, visual disorder, visual impairment - impairment of the sense of sight