filter

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A porous material through which a liquid or gas is passed in order to separate the fluid from suspended particulate matter.
2. n. A device containing such a material, especially one used to extract impurities from air or water.
3. n. Any of various electric, electronic, acoustic, or optical devices used to reject signals, vibrations, or radiations of certain frequencies while allowing others to pass.
4. n. A colored glass or other transparent material used to select the wavelengths of light allowed to reach a photosensitive material.
5. n. Computer Science A program or routine that blocks access to data that meet a particular criterion: a Web filter that screens out vulgar sites.
6. v. To pass (a liquid or gas) through a filter.
7. v. To remove by passing through a filter: filter out impurities.
8. v. Computer Science To use a filter to block access to (a website or Web content).
9. v. To pass through or as if through a filter: Light filtered through the blinds.
10. v. To come or go gradually and in small groups: The audience filtered back into the hall.

Century Dictionary and Cyclopedia

1. n. A device for arresting and separating any matter mechanically suspended in a liquid. Filters used in the processes of analytical chemistry are made of paper or asbestos. The filter-paper is bibulous, consisting of nearly pure cellulose, with only bare traces of mineral matter. Many precipitates are more conveniently separated by an asbestos filter, the most common form consisting of an ordinary platinum crucible having the bottom perforated with fine holes which are covered with a thin asbestos felt. In the arts filters are used to purify water, syrups, vinegar, the juices of cane and fruits, oils, liquors, sewage, liquid by-products, and molten metals. The materials used in filtration are gravel, sand, charcoal, bone-black, sponge, fabrics, woven wire netting, asbestos, porous brick and stone, mineral wool, rope, paper, and powdered glass. The devices used to hold the straining material are in a great variety of forms, from a simple wick or loose cloth hung over the edge of a bowl of water and acting as a capillary strainer, to a settling-pond filtering 400,000 gallons of water in a day. The most common filter is a cone of bibulous paper, or a square of cloth sewed together to form a bag (called Hippocrates's sleeve). Filters also consist of porous brick or stone partitions, as in a cistern, or vessels partly filled with sand and gravel, or tubes filled with sponge, charcoal, or sand, etc. Domestic filters are used in connection with pumps and water-faucets. To cause the liquid to pass through a filter, the weight of a column of water, the pressure of the atmosphere, mechanical force from a screw or from steam-pressure, and centrifugal force are employed, as in the centrifugal filter, oil-filter, vacuum-filter, and many forms of pressure-filters. Filters are also made reversible and intermittent, so that the filtering material may be freed from the collected sediment. In some pressure-filters the liquid or syrup is within a cylinder, and is forced outward through rings of fabric under steam-pressure; in others it is forced through a series of strainers piled one above another. Where bone-black and charcoal are used, there is also a filtering or straining of a certain amount of gas and organic material that would pass through any other filter without detention. Filters are also used to remove dust and floating matter from air, but such devices are more properly termed air-strainers.
2. n. Specifically In fish-culture, a long box in which screens, usually of flannel, are placed, through which the water is filtered before it passes into the hatching-troughs. Also called filtering-box, filtering-tank.
3. To purify or defecate, as water or other liquid, by passing it through a filter or any cleansing medium; strain.
4. Specifically In analytic chemistry, to separate (a solution) from the solid matter contained in it, either for the purpose of collecting and saving the solid matter, usually a precipitate, or of preparing the solution for further operations.
5. To percolate; pass through or as through a filter.
6. Same as felter.
7. n. See philter.

Wiktionary

1. n. A device which separates a suspended, dissolved, or particulate matter from a fluid, solution, or other substance; any device that separates one substance from another.
2. n. Electronics or software that separates unwanted signals (for example noise) from wanted signals or that attenuates selected frequencies.
3. n. Any item, mechanism, device or procedure that acts to separate or isolate.
4. n. mathematics, order theory A non-empty upper set (of a partially ordered set) which is closed under binary infima (a.k.a. meets).
5. v. transitive To sort, sift, or isolate.
6. v. transitive To diffuse; to cause to be less concentrated or focused.
7. v. intransitive To pass through a filter or to act as though passing through a filter.
8. v. intransitive To move slowly or gradually; to come or go a few at a time.
9. v. intransitive To ride a motorcycle between lanes on a road

GNU Webster's 1913

1. n. Any porous substance, as cloth, paper, sand, or charcoal, through which water or other liquid may passed to cleanse it from the solid or impure matter held in suspension; a chamber or device containing such substance; a strainer; also, a similar device for purifying air.
2. v. To purify or defecate, as water or other liquid, by causing it to pass through a filter.
3. v. To pass through a filter; to percolate.
4. n. Same as philter.

WordNet 3.0

1. v. run or flow slowly, as in drops or in an unsteady stream
2. v. pass through
3. v. remove by passing through a filter
4. n. an electrical device that alters the frequency spectrum of signals passing through it
5. n. device that removes something from whatever passes through it