inability to distinguish one or several chromatic colors, independent of the capacity for distinguishing light and shade.
2.
complete inability to distinguish colors of the spectrum, with all objects appearing as shades of gray, black, and white, varying only as to lightness and darkness; achromatopsia.
1844, replacing Daltonism (after Eng. chemist John Dalton, 1766-1844, who published a description of it in 1794); in fig, use, with ref. to race or ethnicity, attested from 1866, Amer.Eng. Related: color blind.