/ Dictionary / Index D daltonism: Meaning and Definition of Find definitions for: dal•ton•ism Pronunciation: (dôl'tn-iz"um), [key] — n. Pathol. color blindness, esp. the inability to distinguish red from green. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: daltonism (Thesaurus) Daltonian Dalton's law Related Content Daily Word Quiz: portent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language