filter

noun fil·ter \ ˈfil-tər \

|Updated on: 19 Jun 2018

Definition of filter

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

See filter defined for English-language learners

See filter defined for kids

Examples of filter in a Sentence

She smokes cigarettes with filters.
He placed a red filter on the camera lens.
digital filters that stop high-frequency sounds

Recent Examples of filter from the Web

In the pic, Khloé is using the tropical flower Snapchat filter, which adds a flower to your hair and a sprinkling of freckles across your nose.

— kayleigh roberts, Marie Claire, "Khloé Kardashian Just Shared Her First Selfie with Baby True," 27 May 2018
The state will soon close the last four locations where Flint residents have been getting free bottled water, filters, replacement cartridges and testing kits, as early as this week.

— paula rogo, Essence.com, "Michigan Will Stop Providing Free Water To Flint Residents Despite Elevated Lead In School Water," 9 Apr. 2018
Also, change filters in your heating and air conditioning system.

— debbie arrington, sacbee, "Time change a reminder to make safety, irrigation checks | The Sacramento Bee," 9 Mar. 2018
Historic female inventors have created the first coffee filters, ice cream maker, life rafts, and even the home security system!

— Indianapolis Star, "Name that Famous Female Inventor," 22 Feb. 2018
In 2016, waterworks sought a contractor to replace sand filters, a $685,000 job.

— mark curnutte, Cincinnati.com, "Cranley vs. Seelbach: Which program puts the most people to work?," 7 Feb. 2018
Addressing these issues with a vet’s help can be transformative for allergic humans, too. Change air conditioning filters.

— dr. patty khuly, miamiherald, "Allergic to your furry friends? Here are tips to help manage pet allergies," 31 May 2018
The map has several filters, most of them typical—think origin airport, and month of travel.

— bridget hallinan, Condé Nast Traveler, "Norwegian Air Now Lets You Book Flights Based on Temperature," 23 May 2018
But there are still UV hair filters with solid science behind them.

— elizabeth siegel, Allure, "7 New Ways to Boost Your Hair-Care Routine This Year," 16 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'filter.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of filter

Middle English filtre, from Medieval Latin filtrum piece of felt used as a filter, of Germanic origin; akin to Old High German filz felt — more at felt

NEW! Time Traveler

First Known Use: 15th century

in the meaning defined at sense 1a

See Words from the same year

Other Chemical Engineering Terms

alkali, cation, decant, hygroscopic, isotope, oxidize, slurry, solute, viscous

filter

verb

Definition of filter

filtered; filtering play \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

See filter defined for English-language learners

Examples of filter in a Sentence

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 of filter from the Web

Less than 5 millimeters long, they're not filtered by washing machines or water treatment plants and have been found in everything from bottled water to sea salt to fish.

— the washington post, NOLA.com, "Your polyester shirt may be polluting our water system," 6 June 2018
All workers must wear full-body clean room suits, the air is filtered to prevent any bacteria from sneaking in, and the spacecraft and all other equipment are regularly sprayed with an industrial solvent.

— avery thompson, Popular Mechanics, "It Turns Out Bacteria Can Eat the Chemicals NASA Puts on Spacecraft to Kill Them," 6 June 2018
Bring sleeping bags, pads, all cooking gear and fuel, and plenty of food and water (there are few options for fresh water, and everything must be filtered).

— erin kirkland, Anchorage Daily News, "Tonsina Point near Seward provides a perfect place for Alaska’s newest public-use cabin," 14 May 2018
My mother is a product of the generation before my own, one which oftentimes fails to realize that perhaps certain conversation should be filtered — or avoided entirely — when children are present.

— pauline campos, Longreads, "You Are What You Hear," 12 Jan. 2018
The security guard had mentioned that the wine hadn’t yet been filtered, but Liu and Fatty didn’t seem bothered.

— steven strogatz, The New Yorker, "Can Wine Transform China’s Countryside?," 4 Feb. 2013
Your boyfriend’s idea for the translucent privacy window film is a good DIY solution if you like filtered light and don’t mind not being able to adjust it.

— jennifer adams, Philly.com, "Ask Jennifer Adams: How to balance outside views and privacy with window treatments," 1 June 2018
Indoor pollutants are filtered through the plants’ root systems, said Heather Mulvihill, Naava’s U.S. business-development manager.

— WSJ, "When Your Home Has Its Very Own Jungle," 24 May 2018
Sharon Horgan’s Catastrophe has a similar comical mindset toward the grubbiness of parenting, though filtered through a more dramatic lens.

— chloe schama, Vogue, "Tig Notaro's New Netflix Special Finds her Content, Healthy, and Just as Funny," 22 May 2018

First Known Use of filter

1576

in the meaning defined at transitive sense 1

See Words from the same year

NEW! Time Traveler

filter Synonyms

FILTER Defined for English Language Learners

filter

noun

Definition of filter for English Language Learners

: a device that is used to remove something unwanted from a liquid or gas that passes through it
: a device that prevents some kinds of light, sound, electronic noises, etc., from passing through
computers : software that prevents someone from looking at or receiving particular kinds of material through the Internet

filter

verb

Definition of filter for English Language Learners

: to pass (something, such as a gas or liquid) through a filter to remove something unwanted
: to remove (something unwanted) by using a filter
: to move through or into something in small amounts or in a gradual way

FILTER Defined for Kids

filter

noun fil·ter \ ˈfil-tər \

Definition of filter for Students

1 : a device or a mass of material (as sand or paper) with tiny openings through which a gas or liquid is passed to remove something

The filter removes dust from the air.

2 : a transparent material that absorbs light of some colors and is used for changing light (as in photography)

filter

verb

Definition of filter for Students

filtered; filtering

1 : to pass through a filter

filter water

2 : to remove by means of a filter

Sand helps filter impurities from water.

Medical Dictionary

filter

noun fil·ter \ ˈfil-tər \

medical Definition of filter

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