tree vs arborous

tree is a noun but arborous is not a noun.

Word	Noun	Adjective	Verb	Adverb
tree	Yes	No	Yes	No
arborous	No	Yes	No	No

tree (noun)	arborous (noun)
a tall perennial woody plant having a main trunk and branches forming a distinct elevated crown; includes both gymnosperms and angiosperms
a figure that branches from a single root

tree (adjective)	arborous (adjective)
	of or relating to or formed by trees

tree (verb)	arborous (verb)
stretch (a shoe) on a shoetree
chase an animal up a tree
plant with trees
force a person or an animal into a position from which he cannot escape