Definition of filter in English:

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Pronunciation: /ˈfɪltə/


1A porous device for removing impurities or solid particles from a liquid or gas passed through it: an oil filter
More example sentences
  • After passing through a filter, the oil and fuel mixture is put into the vehicle's fuel tank to be burned as fuel.
  • Despite manufacturer claims, ozone filters don't remove particles from the air, including those that cause most allergies.
  • And you have to run the car to make the oil hot before you drain the oil and take the filter off.
strainer, sifter;
sieve, riddle, colander;
gauze, netting
1.1A filter tip: [as modifier]: a cheap filter cigarette
More example sentences
  • This been accomplished by the use of filters and filter ventilation, modified cigarette paper and modified forms of tobacco and tobacco blends.
  • You'd think that not having to add a filter would make the cigarette cheaper, but that doesn't seem to be the case.
  • The filters attach to cigarettes and gradually reduce the amount of nicotine consumed.
1.2A screen, plate, or layer of a substance which absorbs light or other radiation or selectively absorbs some of its components: filters can be used in photography to reduce haze
More example sentences
  • As a serious photography project, this is one time you do not need wide angle lenses, special filters or off camera flash guns.
  • Digital cameras can also mount filters, auxiliary lenses and polarizers allowing you to meet any photographic challenge you might come across with.
  • A screen on the light box filters out ultraviolet rays.
1.3A device for suppressing electrical or sound waves of frequencies not required.
Example sentences
  • Passive components are capacitors, resistors, connectors, filters, inductors, and oscillators.
  • Product groups include passive and electromechanical components, capacitors, resistive products, ferrites, fuses, inductors and filters.
  • An electronic filter prevents frequencies from reaching the speakers that are not supposed to receive them.
1.4 Computing A piece of software that processes data before passing it to another application, for example to reformat characters or to remove unwanted types of material.
Example sentences
  • While half the respondents have Internet access, only a third use software filters to block racy or undesirable Web sites.
  • Most search engines have duplication filters in effect that look past formatting changes and do a very good job of detecting duplicate content.
  • That will speed up download times and should allow software filters to be reinstalled, to the relief of teachers and parents.
2British An arrangement whereby vehicles may turn left (or right) while other traffic waiting to go straight ahead or turn right (or left) is stopped by a red light: [as modifier]: a filter lane
More example sentences
  • Other drivers have shown me of their mastery of the finer computer games by their willingness to travel at speeds outside of the law and by the use of filter lanes to avoid stopping.
  • In another country I know well an inexpensive and very efficient system is to use a filter which enables traffic to keep on the move and cuts down on frustration and exhaust fumes which here are pretty bad.
  • The Pontiac was travelling north along Bonnet Creek Road in the left-hand filter lane while the Ford van was travelling south on the inside lane, according to police in Florida.
2.1A traffic light signalling a filter arrangement.
Example sentences
  • Several traders suggested introducing a green filter at the traffic lights in Cricklade Road to allow cars to turn right easier.
  • Then, curiously, a leftturn filter arrow was installed at the traffic lights, replacing a ‘yield’ sign.
  • Good news for motorists - a filter light for traffic existing from Athy Road on to the Main Street is also in the pipeline.


1 [with object] Pass (a liquid, gas, light, or sound) through a device to remove unwanted material: the eye filters out ultraviolet radiation
More example sentences
  • The new one is lighter, can filter unnecessary noise, and is more durable.
  • Fish sauce is what you get when you leave anchovies or similar small fish to pickle in brine until nearly dissolved, and then filter the resulting liquid.
  • His ears filtered the sounds around him, alerting his mind only when a familiar sound crossed his path.
sieve, strain, sift, filtrate, riddle;
clarify, purify, clear, clean, make pure, refine, treat, process, decontaminate
1.1Process or assess (items) in order to reject those that are unwanted: you’ll be put through to a secretary whose job it is to filter calls the brain has the ability to filter out information it considers non-essential
1.2 Computing Process or treat with a filter.
Example sentences
  • Some of you said we're overplaying the privacy concerns involved in trusting ISPs or managed services providers to filter malicious messages from email traffic.
  • There's really no good reason to get caught out: simply filtering executable attachments from emails will guard against this virus.
  • Of course, users may be tempted to filter all server error messages, but that's not a reliable solution because doing so would also block legitimate mail server error messages.
2 [no object, with adverbial of direction] Move slowly in a specified direction: the players filtered out on to the pitch
More example sentences
  • At least an academy has been established, and young players are filtering upwards from it.
  • It filters down through our players to the public through the press.
  • Or how it filters down to the players and becomes the chemistry that fuels champions.
2.1(Of light or sound) enter a place slowly or in small quantities: sunlight filtered in through the thin curtains
More example sentences
  • With a sigh she looked up, propping her head on one hand and watching dust motes dance in the rays of sunlight filtering down from above.
  • As the morning passed, and the sun rose higher in the sky, dappled rays of sunlight filtered through the dense canopy of the jungle, creating dancing patterns on the floor.
  • Only faint rays of sunlight filtered through the thick leaves overhead.
2.2(Of information) gradually become known: the news began to filter in from the hospital
More example sentences
  • Gradually the news filtered through that the latest incidents were nowhere near as bad as the bombings a fortnight ago.
  • While there has been no word from her, the woman believes information will filter through to the foreign country she is living in.
  • Then the information filtered through to East End Park that Gary Holt had been called up to the international squad.
2.3British (Of traffic) be allowed to pass to the left or right at a junction while traffic going straight ahead is halted.
Example sentences
  • At 8am, traffic filtered around the closed-off Cricklade Street smoothly, but as the morning wore on, vehicles began to build up in Devizes Road and Albert Street.
  • The problem with the whole system is it is putting too much pressure on Main Street as the traffic cannot filter through New Street anymore.
  • She said new traffic lights were helping Park & Ride motorists as they filtered on to the A19 towards the roundabout, at the expense of people already on the A19.


Late Middle English (denoting a piece of felt): from French filtre, from medieval Latin filtrum 'felt used as a filter', of West Germanic origin and related to felt1.

Words that rhyme with filter

kilter, philtre (US philter), quilter, tilter

For editors and proofreaders

Line breaks: fil¦ter

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