ETYM Cf. French fondamental.
1. Being or involving basic facts or principles; SYN. rudimentary, underlying.
2. Far-reaching and thoroughgoing in effect especially on the nature of something; SYN. profound.
The lowest tone of a harmonic series; SYN. fundamental frequency, first harmonic.
In musical acoustics, the lowest harmonic of a musical tone, corresponding to the audible pitch.
first harmonic · fundamental frequency