monochromatic vision vs monochromacy

monochromatic vision and monochromacy both are nouns.

Word	Noun	Adjective	Verb	Adverb
monochromatic vision	Yes	No	No	No
monochromacy	Yes	No	No	No

As nouns, monochromatic vision and monochromacy are synonyms defined as:

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

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

monochromatic vision (noun)	monochromacy (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