A layer of gravel, sand, or other material through which liquid is passed in order to remove impurities; also, a pond or tank containing such a layer.

plural of notch filter

(signal processing) A bandstop filter with a narrow stopband.

plural of interference filter

plural of filter bed

A very thick filter paper or a pad composed of several filter papers

A relatively thick, stiff filter paper / A similar card used to hold biological liquid samples

(Jersey, Guernsey) A kind of road junction where all traffic has equal priority regardless of the direction of travel.

plural of bogon filter

simple past tense and past participle of filter down