1. serving as, or being an essential part of, a foundation or basis; basic; underlying: fundamental principles; the fundamental structure.
2. of, relating to, or affecting the foundation or basis: a fundamental revision.
3. being an original or primary source: a fundamental idea.
4. Music. (of a chord) having its root as its lowest note.
5. 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.
6. Also called fundamental note, fundamental tone. Music.
a. the root of a chord.
b. the generator of a series of harmonics.
7. Physics. the component of lowest frequency in a composite wave.
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1. indispensable, primary.
Origin: 1400-50; late Middle English < Medieval Latin fundāmentālis of, belonging to a foundation. See fundament, -al
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