[1] : The Collaborative International Dictionary of English v.0.48

daltonism \dal"tonism\, 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

[2] : WordNet (r) 2.0

daltonism
     n : dichromacy characterized by a lowered sensitivity to green
         light resulting in an inability to distinguish green and
         purplish-red syn: deuteranopia, green-blindness
see also:
deuteranopia green-blindness 

Daltonism >> D Words
Daltonism, definition of term: Daltonism
daltonism_pag1.html