A filter designed to transmit electromagnetic frequencies below a certain value, while excluding those of a higher frequency.
A filter that blocks high frequencies and allows lower frequencies to pass through. Such filters are used in devices such as POTS splitters that direct phone and DSL signals to different lines. Contrast with high-pass filter.
A device that passes all signals below a designated frequency (electrical) or wavelength (optical) band, but absorbs, attenuates, blocks, rejects, or removes all other signals. See also absorption, attenuation, band, band-pass filter, electrical, frequency, high-pass filter, optical, signal, and wavelength.