important vs fundamental

important is not a noun while fundamental is a noun.

Word	Noun	Adjective	Verb	Adverb
important	No	Yes	No	No
fundamental	Yes	Yes	No	No

important (noun)	fundamental (noun)
	the lowest tone of a harmonic series
	any factor that could be considered important to the understanding of a particular business

important (adjective)	fundamental (adjective)
of great significance or value	being or involving basic facts or principles
of extreme importance; vital to the resolution of a crisis	serving as an essential component
important in effect or meaning	far-reaching and thoroughgoing in effect especially on the nature of something
having or suggesting a consciousness of high position
having authority or ascendancy or influence