We present a temperature-dependent Raman scattering study of CdO in the temperature range between 80 and 500 K. Distinctive features present in the second-order Raman spectra of CdO are identified as overtones and combination modes with the help of density functional perturbation theory calculations. A wide, broad band in the region between 250 and $470{\mathrm{cm}}^{-1}$ is attributed to Raman scattering by charge-density fluctuations in the high-density overdamped electron gas present in the sample. Very good agreement is found between the Raman spectra and the expected scattering arising from the overtone density of states and plasmon excitations. The temperature dependence of the modes yields information about the anharmonic phonon interactions. Four-phonon processes arising from quartic anharmonicity play a significant role in the observed temperature dependence.

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