color blindness

n. The inability to perceive a normal range of colors, which may be total or partial. In total color blindness an individual perceives only black, white, and shades of gray. In partial color blindness an individual can lack the capacity to distinguish red, blue, or green colors, depending on which type of photoreceptors are absent form her/his eyes. Most color blindness is inherited and is sex linked but it may also be caused by trauma or disease. Inability to distinguish between red and green is the most common form of color blindness.