An example of a cutoff frequency is a frequency above where a radio stops working.
cutoff frequency - Computer Definition
Referring to the frequency above or below which a band-pass filter absorbs, attenuates, blocks, rejects, or removes signals, allowing only the signals within the designated band to pass through. Generally, the filter introduces insertion loss of 3 dB or more, which results in signal attenuation of 50 percent or more. See also absorption, attenuation, band, band-pass filter, dB, frequency, insertion loss, and signal.