undershrub vs bush

undershrub and bush both are nouns.

Word	Noun	Adjective	Verb	Adverb
undershrub	Yes	No	No	No
bush	Yes	Yes	Yes	No

As nouns, bush is a hypernym of undershrub; that is, bush is a word with a broader meaning than undershrub:

Other hypernyms of undershrub include shrub.

undershrub (noun)	bush (noun)
a low shrub	hair growing in the pubic area
	dense vegetation consisting of stunted trees or bushes
	a large wilderness area
	a low woody perennial plant usually having several major stems

undershrub (adjective)	bush (adjective)
	not of the highest quality or sophistication

undershrub (verb)	bush (verb)
	provide with a bushing