spectral color vs colouring

spectral color and colouring both are nouns.

Word	Noun	Adjective	Verb	Adverb
spectral color	Yes	No	No	No
colouring	Yes	No	No	No

As nouns, colouring is a hypernym of spectral color; that is, colouring is a word with a broader meaning than spectral color:

spectral color: a color that has hue
colouring: a visual attribute of things that results from the light they emit or transmit or reflect

Other hypernyms of spectral color include color, coloring, colour.

spectral color (noun)	colouring (noun)
a color that has hue	the act or process of changing the color of something
	a visual attribute of things that results from the light they emit or transmit or reflect
	a digestible substance used to give color to food