serving as, or being an essential part of, a foundation or basis; basic; underlying

fundamental principles; the fundamental structure.

of, pertaining to, or affecting the foundation or basis

a fundamental revision.

being an original or primary source

a fundamental idea.

Music . (of a chord) having its root as its lowest note.

a basic principle, rule, law, or the like, that serves as the groundwork of a system; essential part

to master the fundamentals of a trade.

Also called fundamental note, fundamental tone. Music .

the root of a chord.

the generator of a series of harmonics.

Physics . the component of lowest frequency in a composite wave.

adverb

radically , centrally , essentially , basically