Band rejected filter

An electronic filter that rejects, or attenuates, a band of frequencies, while passing with little loss all frequencies on either side of this band.

In signal processing, a band-stop filter or band-rejection filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels. It is the opposite of a band-pass filter. A notch filter is a band-stop filter with a narrow stopband (high Q factor).