filter

1 of 2

noun

fil·​ter ˈfil-tər 

1

a

: a porous article or mass (as of paper or sand) through which a gas or liquid is passed to separate out matter in suspension

b

: an apparatus containing a filter medium

2

a

: a device or material for suppressing or minimizing waves or oscillations of certain frequencies (as of electricity, light, or sound)

b

: a transparent material (such as colored glass) that absorbs light of certain wavelengths or colors selectively and is used for modifying light that reaches a sensitized photographic material

called also color filter

3

: something that has the effect of a filter (as by holding back elements or modifying the appearance of something)

his work is too often viewed through the filter of race

—Brent Staples

4

: software for sorting or blocking access to certain online material

filter

2 of 2

verb

filtered; filtering ˈfil-t(ə-)riŋ 

transitive verb

1

: to subject to the action of a filter

2

: to remove by means of a filter

intransitive verb

1

: to pass or move through or as if through a filter

2

: to come or go in small units over a period of time

people began filtering in

Synonyms

Verb

• screen
• strain

Examples of filter in a Sentence

Noun

She smokes cigarettes with filters.

He placed a red filter on the camera lens.

digital filters that stop high-frequency sounds

Verb

They've begun filtering their water to remove impurities.

a device that filters impurities from water

sunglasses that filter ultraviolet light

Sunlight filtered through the leaves.

His ideas have filtered down to his children.

The crowd filtered into the arena.

Early election returns have begun to filter in.

Recent Examples on the Web

Noun

Given that the federal rule will take several years to go into effect, Rumpler recommends that people concerned about PFAS in their drinking water buy a filter designed to catch the chemicals. —Kaitlin Sullivan, Health, 20 Apr. 2024

Some refrigerators also are equipped with water filters that can remove or reduce PFAS. —Mary Divine, Twin Cities, 18 Apr. 2024

Word History

Etymology

Noun

Middle English filtre "felt, felt carpet, piece of felt used as a filter," borrowed from Medieval Latin filtrum "felt cloth, cover or blanket of felt, piece of felt used as a filter," borrowed from *filtir (going back to *filtizō) in a West Germanic language, plural of *filt-, *felt- "felted cloth" — more at felt entry 1

Verb

derivative of filter entry 1

First Known Use

Noun

15th century, in the meaning defined at sense 1a

Verb

1576, in the meaning defined at transitive sense 1

Phrases Containing filter

• band-pass filter
• color filter
• filter bed
• filter bubble
• filter feeder
• filter paper
• filter tip
• spam filter

Kids Definition

filter

1 of 2 noun

fil·​ter ˈfil-tər 

1

: a substance with pores through which a gas or liquid is passed to separate out floating matter

2

: a device containing a filter

3

: a transparent material (as colored glass) that absorbs light of some wavelengths and is used to change light (as in photography)

filter

2 of 2 verb

filtered; filtering -t(ə-)riŋ 

1

: to expose to the action of a filter

2

: to remove by means of a filter

3

: to pass through or as if through a filter

Medical Definition

filter

1 of 2 noun

fil·​ter ˈfil-tər 

1

: a porous article or mass (as of paper or sand) through which a gas or liquid is passed to separate out matter in suspension

2

: an apparatus containing a filter medium

3

a

: a device or material for suppressing or minimizing waves or oscillations of certain frequencies (as of electricity, light, or sound)

b

: a transparent material (as colored glass) that absorbs light of certain wavelengths or colors selectively and is used for modifying light that reaches a sensitized photographic material

called also color filter

filter

2 of 2 verb

filtered; filtering -t(ə-)riŋ 

transitive verb

1

: to subject to the action of a filter

2

: to remove by means of a filter

intransitive verb

: to pass or move through or as if through a filter