Daltonism n 1: dichromacy characterized by a lowered sensitivity to green light resulting in an inability to distinguish green and purplish-red [syn: {deuteranopia}, {Daltonism}, {green- blindness}]
Daltonism \Dal"ton*ism\, 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. --Nichol. [1913 Webster]