purpleness vs violet

purpleness and violet both are nouns.

Word	Noun	Adjective	Verb	Adverb
purpleness	Yes	No	No	No
violet	Yes	Yes	No	No

As nouns, violet is a hyponym of purpleness; that is, violet is a word with a more specific, narrower meaning than purpleness:

Other hyponyms of purpleness include lavender, mauve, reddish purple, royal purple, reddish blue.

purpleness (noun)	violet (noun)
a color between red and blue	a variable color that lies beyond blue in the spectrum
	any of numerous low-growing violas with small flowers

purpleness (adjective)	violet (adjective)
	of a color intermediate between red and blue