violet vs reddish blue

violet and reddish blue both are nouns.

Word	Noun	Adjective	Verb	Adverb
violet	Yes	Yes	No	No
reddish blue	Yes	No	No	No

As nouns, violet and reddish blue are synonyms defined as:

violet and reddish blue: a variable color that lies beyond blue in the spectrum

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

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