Is it ensure, insure, or assure?
1844, replacing Daltonism (after English chemist John Dalton, 1766-1844, who published a description of it in 1794); in figurative use, with reference to race or ethnicity, attested from 1866, American English. Related: color blind (adj.).
color blindness n.
Deficiency of color perception, whether hereditary or acquired, partial or complete.