(n.) Inability to perceive or distinguish certain colors, esp. red; color blindness. It has various forms and degrees. So called from the chemist Dalton, who had this infirmity.

Christmas disease Daltonism Hartnup disease Werdnig-Hoffmann disease achromatic vision achromatopsia albinism cystic fibrosis deuteranopia dichromatic vision dichromatism dysautonomia green blindness hemophilia ichthyosis mongolianism mongolism monochromatism mucoviscidosis muscular dystrophy pancreatic fibrosis protanopia red-green blindness sickle-cell anemia thalassemia tritanopia violet-blindness xanthocyanopia yellow blindness