underwood vs wood

underwood and wood both are nouns.

Word	Noun	Adjective	Verb	Adverb
underwood	Yes	No	No	No
wood	Yes	No	No	No

underwood (noun)	wood (noun)
the brush (small trees and bushes and ferns etc.) growing beneath taller trees in a wood or forest	any wind instrument other than the brass instruments
	a golf club with a long shaft used to hit long shots; originally made with a wooden head
	the trees and other plants in a large densely wooded area
	the hard fibrous lignified substance under the bark of trees