From Longman Dictionary of Contemporary Englishfilterfil‧ter1 /ˈfɪltə $ -ər/ ●●○ noun [countable] 1 TSEPARATEsomething that you pass water, air etc through in order to remove unwanted substances and make it clean or suitable to usewater/air/oil etc filter a pond filter coffee filter papers filter cigarettes (=with a filter at the end)2 Ca piece of equipment or computer program that only allows certain sounds, images, signals, types of information etc to pass through it a UVA light filter The firm uses electronic filters to prevent workers from accessing the Internet.3 British EnglishTTC a traffic light that shows car drivers when they can turn right or left
Examples from the Corpus
filter• FiltrationA filter is of great help in keeping water free of suspended material, but it does not alleviate a polluted condition.• An interference filter consists of two thin-silvered pieces of glass which are semitransparent.• Two small filters can be easier to hide than one large one.• The filter was constructed as shown in the diagram and then stood on the wooden crosspieces on top of the vat.• If I build a trickle filter, holding approximately 10 gallons, will I be able to increase my stocking level?• Marine Answers Increasing the stock I have a 34 gallon set up with an undergravel filter and external canister filter.• a water filter• The bi-word filter eliminated some possibilities but was not good enough to find a single interpretation.water/air/oil etc filter• Are you interested in a plumbed-in water filter or would a table-top model suit you better?• I mean. Air filters are, air filters are not one of our best selling items.• However, portable water filters provide another simple alternative.• The remote oil filter pipes rubbed against the sharp edge of the battery bracket.• And it comes with a removable air filter, an extra long cable, fitted plug and a two year guarantee.• The remains of the air filter system was fitted facing the rear bulkhead.• Pardue's aircraft had metal on the oil filter screens as well as part of a piston ring.filterfilter2 ●○○ verb 1 [transitive]SEPARATE to remove unwanted substances from water, air etc by passing it through a special substance or piece of equipment The water in the tank is constantly filtered. The ozone layer filters harmful UV rays from the sun.2 [intransitive always + adverb/preposition]MOVE something OR somebody if people filter somewhere, they move gradually to that place Chattering noisily, the crowd began to filter into the auditorium.3 [intransitive always + adverb/preposition]FIND OUT if news, information etc filters somewhere, people gradually hear about it from each other The news gradually filtered through from Bombay last night.4 [intransitive always + adverb/preposition]C if light or sound filters into a place, it can be seen or heard only slightly Moonlight filtered in through the frosted window. The familiar notes of Beethoven’s ‘Für Elise’ filtered from the bar.5 [intransitive, transitive] British EnglishTTC if traffic filters, or if a system filters it, cars can turn left or right while other vehicles going straight ahead must wait → filter something ↔ out→ See Verb tableExamples from the Corpus
filter• Memory was mischievously selective at the best of times Trivia stuck limpet-like and the useful filtered away.• That software can filter either e-mail or Usenet postings.• In remote areas, you will need to filter or boil your drinking water.• These used rotating discs to initiate a quasi-musical sound which was then filtered, processed and reproduced at different pitches.• These firms know what the local law is, and could filter some Internet content as demanded by it.• When they are exhaled they are filtered through the white crystals of soda lime, and a bacterial filter.Origin filter1 (1300-1400) Old French filtre “piece of felt (= thick material) used as a filter”, from Medieval Latin filtrum 