# what does frequencies in non periodic signals mean?

What do the frequencies in the a Fourier transform of a non-periodic signal mean physically?

Are there another definition of frequency that doesn't include the FT?

• I would like to note that the signal $\sin(t)+\sin(\pi\,t)$ is non-periodic, since the ratio of the frequencies is not rational, but their frequencies clearly are well defined. – fibonatic Jan 2 at 10:47

This infinitesimal frequency component at any $$\omega$$, has no physical significance, unlike the dirac impulse at $$\omega$$, which has a direct implication of a sinusoidal signal component, extending from minus infinity to infinity (in time for example).