olive brown vs brown

olive brown and brown both are nouns.

Word	Noun	Adjective	Verb	Adverb
olive brown	Yes	No	No	No
brown	Yes	Yes	Yes	No

As nouns, brown is a hypernym of olive brown; that is, brown is a word with a broader meaning than olive brown:

Other hypernyms of olive brown include brownness.

olive brown (noun)	brown (noun)
a shade of brown tinged with green	an orange of low brightness and saturation

olive brown (adjective)	brown (adjective)
	(of skin) deeply suntanned
	of a color similar to that of wood or earth

olive brown (verb)	brown (verb)
	fry in a pan until it changes color
	make brown in color