Definition of "filter"

filter

/ˈfɪltə/

noun
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.
  Quotations
  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.
  2013 May 25, “No hiding place”, in The Economist‎, volume 407, number 8837, page 74
4. (figurative) self-restraint in speech.
5. (mathematics, order theory) A non-empty upper set (of a partially ordered set) which is closed under binary infima (a.k.a. meets).
6. (photography) A translucent object placed in the light path of a camera to remove certain wavelengths (colors), or a computer program that simulates such an effect.
verb
third-person singular simple present filters, present participle filtering, simple past and past participle filtered
1. (transitive) To sort, sift, or isolate.
  Quotations
  “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.”
  1954, Alexander Alderson, chapter 5, in The Subtle Minotaur‎
  But fans’ emotions are no longer filtered through ticket or album sales; they’re heard directly, constantly, at all hours, on all the platforms people visit to generate and extinguish bad feelings in a never-ending cycle.
  2022 October 25, Willy Staley, “The Try Guys and the Prison of Online Fame”, in The New York Times Magazine‎
2. (transitive) To diffuse; to cause to be less concentrated or focused.
3. (intransitive) To pass through a filter or to act as though passing through a filter.
4. (intransitive) To move slowly or gradually; to come or go a few at a time.
5. (intransitive) To ride a motorcycle between lanes on a road