chromatic vs chroma

chromatic is not a noun while chroma is a noun.

Word	Noun	Adjective	Verb	Adverb
chromatic	No	Yes	No	No
chroma	Yes	No	No	No

chromatic (noun)	chroma (noun)
	chromatic purity: freedom from dilution with white and hence vivid in hue

chromatic (adjective)	chroma (adjective)
being or having or characterized by hue
based on a scale consisting of 12 semitones
able to refract light without spectral color separation