Harmonic

adj. melodious, consonant, compatible; of or relating to musical harmony

n. overtone, secondary tone which is higher than the primary or fundamental tone (Music)

In acoustics and telecommunication, the harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency. For example, if the frequency is f, the harmonics have frequency 2f, 3f, 4f, etc. The harmonics have the property that they are all periodic at the signal frequency. Also, due to the properties of Fourier series, the sum of the signal and its harmonics is also periodic at that frequency.
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Noun
1. a tone that is a component of a complex sound
(hypernym) tone, pure tone
(hyponym) fundamental, fundamental frequency, first harmonic
Adjective
1. of or relating to harmony as distinct from melody and rhythm; "subtleties of harmonic change and tonality"- Ralph Hill
(antonym) nonharmonic
(pertainym) harmony, musical harmony
2. of or relating to the branch of acoustics that studies the composition of musical sounds; "the sound of the resonating cavity cannot be the only determinant of the harmonic response"
(pertainym) harmonics
3. relating to vibrations that occur as a result of vibrations in a nearby body; "sympathetic vibration"
(synonym) sympathetic
(similar) harmonious
4. involving or characterized by harmony
(synonym) consonant, harmonical, harmonized, harmonised, in harmony
(similar) harmonious

(n.)
A musical note produced by a number of vibrations which is a multiple of the number producing some other; an overtone. See Harmonics.
  

(a.)
Alt. of Harmonical
  

1. Of a sinusoidal wave, an integral multiple of the frequency of the wave. Note: The frequency of the sine wave is called the fundamental frequency or the first harmonic, the second harmonic is twice the fundamental frequency, the third harmonic is thrice the fundamental frequency, etc. 2. Of a periodic signal or other periodic phenomenon, such as an electromagnetic wave or a sound wave, a component frequency of the signal that is an integral multiple of the fundamental frequency. Note: The fundamental frequency is the reciprocal of the period of the periodic phenomenon. Contrast with fundamental, overtone.