filter

Etymology

From Middle English filtre, from Medieval Latin filtrum (compare also Old French feutre (“felt; filter”)), from Frankish *filtir, from Proto-Germanic *feltaz. See felt.

Pronunciation

• (Received Pronunciation) IPA^(key): /ˈfɪltə/
• (General American) IPA^(key): /ˈfɪltɚ/, [ˈfɪɫɾɚ]

• Audio (US)

  (file)

• Rhymes: -ɪltə(r)

Noun

filter (plural filters)

1. 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. Electronics or software that separates unwanted signals (for example noise) from wanted signals or that attenuates selected frequencies.
3. Any item, mechanism, device or procedure that acts to separate or isolate.
   • 2013 May 25, “No hiding place”, in The Economist‎, volume 407, number 8837, page 74:

     In America alone, people spent $170 billion on “direct marketing”—junk mail of both the physical and electronic varieties—last year. Yet of those who received unsolicited adverts through the post, only 3% bought anything as a result. If the bumf arrived electronically, the take-up rate was 0.1%. And for online adverts the “conversion” into sales was a minuscule 0.01%. That means about $165 billion was spent not on drumming up business, but on annoying people, creating landfill and cluttering spam filters.

   He runs an email filter to catch the junk mail.

4. (figuratively) self-restraint in speech.

   He's got no filter, and he's always offending people as a result.

5. (mathematics, order theory) A non-empty upper set (of a partially ordered set) which is closed under binary infima (a.k.a. meets).

   The collection of cofinite subsets of ℝ is a filter under inclusion: it includes the intersection of every pair of its members, and includes every superset of every cofinite set.

   If (1) the universal set (here, the set of natural numbers) were called a "large" set, (2) the superset of any "large" set were also a "large" set, and (3) the intersection of a pair of "large" sets were also a "large" set, then the set of all "large" sets would form a filter.

Verb

filter (third-person singular simple present filters, present participle filtering, simple past and past participle filtered)

1. (transitive) To sort, sift, or isolate.
   • This strainer should filter out the large particles.
   • 1954, Alexander Alderson, chapter 5, in The Subtle Minotaur‎:

     “You have probably never seen anything like this before, Mr. Toler. It is baleen, or if you prefer it, whalebone, taken from the mouth of the bowhead whale. It is used by the whale to filter its food.”

2. (transitive) To diffuse; to cause to be less concentrated or focused.
   • The leaves of the trees filtered the light.
3. (intransitive) To pass through a filter or to act as though passing through a filter.
   • The water filtered through the rock and soil.
4. (intransitive) To move slowly or gradually; to come or go a few at a time.
   • The crowd filtered into the theater.
5. (intransitive) To ride a motorcycle between lanes on a road
   • I can skip past all the traffic on my bike by filtering.

Related terms

• filtrate
• filtration
• filtride

Anagrams

• filtre, firtle, lifter, relift, trifle

Noun

filter n (singular definite filtret or filteret, plural indefinite filtre)

1. filter

Pronunciation

• Audio

  (file)

Noun

filter m, n (plural filters, diminutive filtertje n)

1. filter

Anagrams

• flirte

Verb

filter

1. First-person singular present of filtern.
2. Imperative singular of filtern.

Etymology

From German Filter, from Medieval Latin filtrum.^[1]

Pronunciation

• IPA^(key): [ˈfiltɛr]
• Hyphenation: fil‧ter

Noun

filter

1. filter (any device that separates one substance from another)
2. cigarette filter

References

Etymology

From French filtre

Noun

filter n (definite singular filteret or filtret, indefinite plural filter or filtre, definite plural filtra or filtrene)

1. a filter

References

• “filter” in The Bokmål Dictionary.

Etymology

From French filtre

Noun

filter n (definite singular filteret, indefinite plural filter, definite plural filtera)

1. a filter

References

• “filter” in The Nynorsk Dictionary.

Alternative forms

• fìltar

Pronunciation

• IPA^(key): /fǐlter/
• Hyphenation: fil‧ter

Noun

fìlter m (Cyrillic spelling фѝлтер)

1. filter

Noun

filter n

1. A filter.