Definitions for "Periodogram"
(see spectra) is a plot of variance in each fixed frequency interval versus frequency. [pg 110, 5
A plot of amplitude or squared amplitude against frequency for the wave components of a periodic function represented by a Fourier series.
The term periodogram appears often in the context of power spectral density calculations. In his paper Power Spectral Density estimation, Fernando S. Schlindwein explains the origin of the word 'periodogram'.