Main Entry: ¹fil·ter

Pronunciation: \ˈfil-tər\

Function: noun

1 : a porous article or mass (as of paper or sand) through which a gas or liquid is passed to separate out matter in suspension
2 : an apparatus containing a filter medium
3 a : a device or material for suppressing or minimizing waves or oscillations of certain frequencies (as of electricity, light, or sound) b : a transparent material (as colored glass) that absorbs light of certain wavelengths or colors selectively and is used for modifying light that reaches a sensitized photographic material—called also color filter