The output power achieved when a 10 dB increase in drive level results in only 9 dB of output signal increase. Loosely, it is the maximum output power of an amplifier at which amplification remains nearly linear.

Other compression points such as 0.1 dB or 2 dB are sometimes specified.

The additional transmission loss (in dB) within the 3 dB passband of a filter attributable to the presence of spurious resonance (absorption) modes. Skirt spurious modes are referenced to a line tangent to the YIG filter passband skirt. Spurious modes within the minimum loss (ripple) region are referenced to the normalized filter response curve.