harmonic vs fundamental

harmonic and fundamental both are nouns.

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

As nouns, fundamental is a hyponym of harmonic; that is, fundamental is a word with a more specific, narrower meaning than harmonic:

Other hyponyms of harmonic include first harmonic, fundamental frequency, overtone, partial, partial tone.

harmonic (noun)	fundamental (noun)
any of a series of musical tones whose frequencies are integral multiples of the frequency of a fundamental	the lowest tone of a harmonic series
a tone that is a component of a complex sound	any factor that could be considered important to the understanding of a particular business

harmonic (adjective)	fundamental (adjective)
of or relating to harmony as distinct from melody and rhythm	being or involving basic facts or principles
of or relating to the branch of acoustics that studies the composition of musical sounds	serving as an essential component
of or relating to harmonics	far-reaching and thoroughgoing in effect especially on the nature of something
involving or characterized by harmony
relating to vibrations that occur as a result of vibrations in a nearby body