filter

Pluralfilters

Formsfilters, filtering, filtered

1. 1
   nouncountable

   A device that separates suspended, dissolved, or particulate matter from a fluid or other substance; broadly, anything that separates one substance from another.

   The oil filter prevents debris from circulating through the engine.

   Municipal plants use sand filters to remove sediment before treating the water.

   Similarstrainer, sieve, screen

   Note

   Felt is hiding inside this word. Medieval Latin filtrum goes back through Frankish *filtir to the Germanic root that also gave English felt, and Old French feutre meant both "felt" and "filter." The device and the fabric share one name. Pass something through a filter is the core construction, and the verb senses all grow from it.

2. 2
   verbtransitive

   To sort, sift, or isolate items, keeping some and setting others aside.

   The software filters incoming messages by sender and subject.

   Reviewers filter thousands of submissions down to a handful of finalists.

   Similarsort, sift, screen, winnow

   Note

   The verb takes two kinds of object. With out, the object is what gets removed: a strainer filters out the large particles. Without out, the object is what is being processed. In Alexander Alderson's The Subtle Minotaur (1954), baleen lets a whale filter its food. In the passive, filtered through names the channel something passes through, as in emotions filtered through ticket sales.

3. 3
   nouncountable

   A digital image effect applied to a photo or video to alter its appearance.

   The app's newest filter smooths skin and warms the lighting automatically.

   Influencers often swap filters until the mood of a post feels right.

   Similareffect, preset

   Note

   Social media stretched the photographer's word to cover any effect that changes how an image looks. Its boast comes in the negative. Patent Pending's "All-Star Hipster" (2013) sings of someone who posts photos without one, meaning his photos need no improving. Keep this apart from having no filter in the tactless sense, which is about speech, not looks.

4. 4
   nouncountable

   Electronics or software that separates unwanted signals, such as noise, from wanted ones, or that weakens selected frequencies.

   The engineer added a low-pass filter to remove high-frequency noise from the audio.

   Digital filters in the receiver isolate the desired channel from neighboring frequencies.

5. 5
   nouncountable

   A translucent object placed in a camera's light path to remove certain wavelengths, or a program that simulates the same effect.

   A polarizing filter cut the glare off the lake's surface.

   Landscape photographers stack neutral-density filters for long daytime exposures.

   Note

   A photographer's filter works on light before it reaches the camera's sensor, removing chosen wavelengths. The software kind imitates that optics after the fact. Filters are named for the job they do, such as polarizing or neutral-density. That precise optical job is what sets this sense apart from the social-media effect, which can change a picture's look in any way at all.

6. 6
   verbintransitive

   To pass through a filter, or to move as if passing through one.

   Moonlight filtered through the gaps in the old roof.

   Faint music seemed to filter up from the apartment below.

   Similarseep, trickle, stream, drift, leak

7. 7
   nounfigurativelycountable

   Self-restraint that keeps a person from blurting out blunt or inappropriate remarks.

   After a few drinks, his filter disappeared entirely.

   She admires people who speak with a filter and never wound others carelessly.

   Similartact, discretion, restraint

   Note

   A figurative transfer from the device to the mind: the filter is what stops a thought before it becomes speech. People mostly talk about it when it is missing. Someone has no filter, or loses it after a few drinks, and the phrase usually works as a criticism of how a person speaks to others.

8. 8
   verbintransitive

   To pass from one place to another gradually or in small numbers.

   Commuters filtered onto the platform as the announcement played.

   News of the result began to filter through the crowd.

   Similartrickle, drift, straggle, spread, percolate

   Oppositepour, flood

9. 9
   nouncountable

   Anything, whether a physical device or a process, that serves to separate one thing from another or to screen some out.

   A careful screening process can be a filter for unsuitable products.

   Tradition often works as a filter, isolating the practices a community wants to keep.

   Similarscreen, sieve

10. 10
    verbtransitive

    To diffuse something, making it less concentrated or less sharply focused.

    Sheer drapes filter the daylight into a gentle glow.

    The canopy of leaves filtered the afternoon sun across the path.

    Similardiffuse, soften, dapple

    Oppositefocus, concentrate

    Note

    Here the screen is the subject and the light is its object: the leaves filtered the light. Turn the sentence around and the light becomes the subject of the intransitive verb, filtering through the leaves. Both describe the same scene. Choose this transitive pattern when the screen, whether leaves, drapes or cloud, is what you want to put first.

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