sky-blue vs chromatic

sky-blue is a noun but chromatic is not a noun.

Word	Noun	Adjective	Verb	Adverb
sky-blue	Yes	Yes	No	No
chromatic	No	Yes	No	No

sky-blue (noun)	chromatic (noun)
a light shade of blue

sky-blue (adjective)	chromatic (adjective)
of a deep somewhat purplish blue color similar to that of a clear October sky	being or having or characterized by hue
	based on a scale consisting of 12 semitones
	able to refract light without spectral color separation