Main Entry: ¹fil·ter

Pronunciation: \ˈfil-tər\

Function: noun

Etymology: Middle English filtre, from Medieval Latin filtrum piece of felt used as a filter, of Germanic origin; akin to Old High German filz felt — more at felt

Date: 1563

1 a : a porous article or mass (as of paper or sand) through which a gas or liquid is passed to separate out matter in suspension b : an apparatus containing a filter medium
2 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
3 : something that has the effect of a filter (as by holding back elements or modifying the appearance of something) <his work is too often viewed through the filter of race — Brent Staples>
4 : software for sorting or blocking access to certain online material