fundamental vs of import

fundamental is a noun but of import is not a noun.

Word	Noun	Adjective	Verb	Adverb
fundamental	Yes	Yes	No	No
of import	No	Yes	No	No

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

fundamental (adjective)	of import (adjective)
being or involving basic facts or principles	of great significance or value
serving as an essential component
far-reaching and thoroughgoing in effect especially on the nature of something