ebony vs achromatic

ebony is a noun but achromatic is not a noun.

Word	Noun	Adjective	Verb	Adverb
ebony	Yes	Yes	No	No
achromatic	No	Yes	No	No

ebony (noun)	achromatic (noun)
a very dark black
tropical tree of southern Asia having hard dark-colored heartwood used in cabinetwork
hard dark-colored heartwood of the ebony tree; used in cabinetwork and for piano keys

ebony (adjective)	achromatic (adjective)
of a very dark black	having no hue