monochromacy vs monochromatism

monochromacy and monochromatism both are nouns.

Word	Noun	Adjective	Verb	Adverb
monochromacy	Yes	No	No	No
monochromatism	Yes	No	No	No

As nouns, monochromacy and monochromatism are synonyms defined as:

monochromacy and monochromatism: complete color blindness; colors can be differentiated only on the basis of brightness

Other synonyms of monochromacy include monochromasy, monochromatic vision, monochromia.

monochromacy (noun)	monochromatism (noun)
complete color blindness; colors can be differentiated only on the basis of brightness	complete color blindness; colors can be differentiated only on the basis of brightness