spectral color vs spectral colour

spectral color and spectral colour both are nouns.

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

As nouns, spectral color and spectral colour are synonyms defined as:

Other synonyms of spectral color include chromatic color, chromatic colour.

spectral color (noun)	spectral colour (noun)
a color that has hue	a color that has hue