CIDE DICTIONARY

filter, n. [F. filtre, the same word as feutre felt, LL. filtrum, feltrum, felt, fulled wool, this being used for straining liquors. See Feuter.].

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. [1913 Webster]

Filter bed, a pond, the bottom of which is a filter composed of sand gravel. -- Filter gallery, an underground gallery or tunnel, alongside of a stream, to collect the water that filters through the intervening sand and gravel; -- called also infiltration gallery.

filter, v. t. [Cf. F. filter. See Filter, n., and cf. Filtrate.].

To purify or defecate, as water or other liquid, by causing it to pass through a filter. [1913 Webster]

Filtering paper, or Filter paper, a porous unsized paper, for filtering.

filter, v. i.

To pass through a filter; to percolate. [1913 Webster]

filter, n.

Same as Philter. [1913 Webster]

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OXFORD DICTIONARY

filter, n. & v.
--n.
1 a porous device for removing impurities or solid particles from a liquid or gas passed through it.
2 = filter tip.
3 a screen or attachment for absorbing or modifying light, X-rays, etc.
4 a device for suppressing electrical or sound waves of frequencies not required.
5 Brit. a an arrangement for filtering traffic. b a traffic-light signalling this.
--v.intr. & tr.
1 pass or cause to pass through a filter.
2 (foll. by through, into, etc.) make way gradually.
3 (foll. by out) leak or cause to leak.
4 Brit. allow (traffic) or (of traffic) be allowed to pass to the left or right at a junction while traffic going straight ahead is halted (esp. at traffic lights).

Idiom

filter-bed a tank or pond containing a layer of sand etc. for filtering large quantities of liquid. filter-paper porous paper for filtering. filter tip
1 a filter attached to a cigarette for removing impurities from the inhaled smoke.
2 a cigarette with this. filter-tipped having a filter tip.

Etymology

F filtre f. med.L filtrum felt used as a filter, f. WG

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THESAURUS

filter

bleed, bolt, butterfly, cheesecloth, clarifier, clarify, clean, clear, cloth, colander, condense, cradle, cribble, decrassify, depurate, diffusing screen, discharge, distill, drain, dribble, drip, dripple, drop, edulcorate, effuse, eliminate, elute, emit, essentialize, exclude, excrete, exfiltrate, extract, extravasate, exudate, exude, filtrate, frosted glass, frosted lens, gauze, gelatin filter, give off, ground glass, gurgle, leach, lens hood, light filter, lixiviate, lixiviator, membrane, ooze, pass through, percolate, percolator, purifier, purify, rectify, reek, refine, refiner, refinery, riddle, rocker, run through, screen, seep, separate, sieve, sift, sifter, smoked glass, spiritualize, spurtle, stained glass, strain, strainer, sublimate, sublime, transude, trickle, try, weed out, weep, winnow, winnowing basket, winnowing fan, winnowing machine

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ROGET THESAURUS

filter

Cleanness

N cleanness, cleanliness, purity, cleaning, purification, defecation, purgation, lustration, detersion, abstersion, epuration, mundation, ablution, lavation, colature, disinfection, drainage, sewerage, lavatory, laundry, washhouse, washerwoman, laundress, dhobi, laundryman, washerman, scavenger, dustman, sweep, white wings brush, broom, besom, mop, rake, shovel, sieve, riddle, screen, filter, blotter, napkin, cloth, maukin, malkin, handkerchief, towel, sudary, doyley, doily, duster, sponge, mop, swab, cover, drugget, wash, lotion, detergent, cathartic, purgative, purifier, disinfectant, aperient, benzene, benzine benzol, benolin, bleaching powder, chloride of lime, dentifrice, deobstruent, laxative, clean, cleanly, pure, immaculate, spotless, stainless, taintless, trig, without a stain, unstained, unspotted, unsoiled, unsullied, untainted, uninfected, sweet, sweet as a nut, neat, spruce, tidy, trim, gimp, clean as a new penny, like a cat in pattens, cleaned, kempt, abstergent, cathartic, cleansing, purifying, neatly, clean as a whistle.

VB be clean, render clean, clean, cleanse, mundify, rinse, wring, flush, full, wipe, mop, sponge, scour, swab, scrub, brush up, wash, lave, launder, buck, absterge, deterge, decrassify, clear, purify, depurate, despumate, defecate, purge, expurgate, elutriate, lixiviate, edulcorate, clarify, refine, rack, filter, filtrate, drain, strain, disinfect, fumigate, ventilate, deodorize, whitewash, castrate, emasculate, sift, winnow, pick, weed, comb, rake, brush, sweep, rout out, clear out, sweep out, make a clean sweep of.

Sponge

N sponge, honeycomb, network, frit, filter, sieve, net, screen (opening), cellular, spongy, spongious, honeycombed, alveolar, sintered, porous (opening).

Egress

VB emerge, emanate, issue, egress, go out of, come out of, move out of, pass out of, pour out of, flow out of, pass out of, evacuate, exude, transude, leak, run through, out through, percolate, transcolate, egurgitate, strain, distill, perspire, sweat, drain, ooze, filter, filtrate, dribble, gush, spout, flow out, well, well out, pour, trickle, effuse, extravasate, disembogue, discharge itself, debouch, come forth, break forth, burst out, burst through, find vent, escape.

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