greenish blue vs turquoise

greenish blue and turquoise both are nouns.

Word	Noun	Adjective	Verb	Adverb
greenish blue	Yes	No	No	No
turquoise	Yes	No	No	No

As nouns, greenish blue and turquoise are synonyms defined as:

Other synonyms of greenish blue include aqua, aquamarine, cobalt blue, peacock blue.

greenish blue (noun)	turquoise (noun)
a shade of blue tinged with green	a shade of blue tinged with green
	a blue to grey green mineral consisting of copper aluminum phosphate