geology vs igneous

geology is a noun but igneous is not a noun.

Word	Noun	Adjective	Verb	Adverb
geology	Yes	No	No	No
igneous	No	Yes	No	No

geology (noun)	igneous (noun)
a science that deals with the history of the earth as recorded in rocks

geology (adjective)	igneous (adjective)
	produced by the action of fire or intense heat
	produced under conditions involving intense heat
	like or suggestive of fire