👉 The term "non-frequency" is used in physics and engineering to describe a frequency that is not present in a signal or wave. In other words, it refers to frequencies that are absent from a particular phenomenon or measurement. For example, if you measure the frequency of a sound wave, you can see that it has a specific frequency characteristic, but if you look at the waveform of the sound wave, you will see that it is not in sync with the frequency you measured.
