Wavenumber in Physics is a property of a wave defined as either » the number of wavelengths per unit distance, that is, 1/λ where λ=wavelength, or alternatively as 2π/λ, sometimes termed the angular wavenumber or circular wavenumber or, simply wavenumber. Wavenumber is the spatial analog of frequency. Applying of a Fourier transform to data as a function of time yields a frequency spectrum; application on data as a function of position yields a wavenumber spectrum. In the SI… (More on Wavenumber)