yellow-bellied vs yellow

yellow-bellied is not a noun while yellow is a noun.

Word	Noun	Adjective	Verb	Adverb
yellow-bellied	No	Yes	No	No
yellow	Yes	Yes	Yes	No

As adjectives, yellow-bellied and yellow are synonyms defined as:

Other synonyms of yellow-bellied include chicken, chickenhearted, lily-livered, white-livered.

yellow-bellied (noun)	yellow (noun)
	yellow color or pigment; the chromatic color resembling the hue of sunflowers or ripe lemons

yellow-bellied (adjective)	yellow (adjective)
easily frightened	of the color intermediate between green and orange in the color spectrum; of something resembling the color of an egg yolk
	easily frightened
	cowardly or treacherous
	changed to a yellowish color by age
	typical of tabloids
	affected by jaundice which causes yellowing of skin etc

yellow-bellied (verb)	yellow (verb)
	turn yellow