filter

• • The filter can be:

    sorting principle, selection principle
    a device or substance that does not let something (but lets others)
    in chemistry and technology:
    a device for separating a certain part of a mixture, i.e. an instrument for filtration, see under filtration
    laboratory filter for short
    in physics: a device for absorbing some types of radiation, see filter (radiation)
    in electrical engineering: electrical filter for short
    in photography: photo filter for short
    in optics: optical filter for short
    in geology: a layer of matter permeable to surface water to lower layers, see filter (surface water)
    in the military: part of a protective mask, see filter (protective mask)
    in mining: a device preventing sand or other fine material from entering the well during rock drainage, see filter (mining)
    in air engineering: air filter for short
    water filter for short
    aquarium aid for water purification, see filter (aquaristics)
    in mathematics:
    custom filter for short
    dual ideal
    in computer science:
    a program that processes a passing data stream, see filter (computer science)
    methods for selecting data that can be accessed on the Internet, see filter (Internet)