fibrous vs fiber

fibrous is not a noun while fiber is a noun.

Word	Noun	Adjective	Verb	Adverb
fibrous	No	Yes	No	No
fiber	Yes	No	No	No

fibrous (noun)	fiber (noun)
	a leatherlike material made by compressing layers of paper or cloth
	the inherent complex of attributes that determines a persons moral and ethical actions and reactions
	any of several elongated, threadlike cells (especially a muscle fiber or a nerve fiber)
	coarse, indigestible plant food low in nutrients; its bulk stimulates intestinal peristalsis
	a slender and greatly elongated substance capable of being spun into yarn

fibrous (adjective)	fiber (adjective)
(of meat) full of sinews; especially impossible to chew
having or resembling fibers especially fibers used in making cordage such as those of jute