From The Collaborative International Dictionary of English v.0.48 :
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]From WordNet (r) 3.0 (2006) :
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]