intravenous vs vein

intravenous is not a noun while vein is a noun.

Word	Noun	Adjective	Verb	Adverb
intravenous	No	Yes	No	No
vein	Yes	No	Yes	No

intravenous (noun)	vein (noun)
	one of the horny ribs that stiffen and support the wing of an insect
	a blood vessel that carries blood from the capillaries toward the heart
	a distinctive style or manner
	a layer of ore between layers of rock
	any of the vascular bundles or ribs that form the branching framework of conducting and supporting tissues in a leaf or other plant organ

intravenous (adjective)	vein (adjective)
within or by means of a vein

intravenous (verb)	vein (verb)
	make a veinlike pattern