lemon yellow vs lemon

lemon yellow and lemon both are nouns.

Word	Noun	Adjective	Verb	Adverb
lemon yellow	Yes	No	No	No
lemon	Yes	No	No	No

As nouns, lemon yellow and lemon are synonyms defined as:

Other synonyms of lemon yellow include gamboge, maize.

lemon yellow (noun)	lemon (noun)
a strong yellow color	an artifact (especially an automobile) that is defective or unsatisfactory
	a strong yellow color
	a distinctive tart flavor characteristic of lemons
	yellow oval fruit with juicy acidic flesh
	a small evergreen tree that originated in Asia but is widely cultivated for its fruit