plural filters
1
: a device that is used to remove something unwanted from a liquid or gas that passes through it
She smokes cigarettes with filters.
a water filter
2
: a device that prevents some kinds of light, sound, electronic noises, etc., from passing through
He placed a red filter on the camera lens.
digital filters that stop high-frequency sounds
3
computers
: software that prevents someone from looking at or receiving particular kinds of material through the Internet
a spam filter [=a program that keeps you from seeing spam or unwanted e-mail]
filters; filtered; filtering
1
a
: to pass (something, such as a gas or liquid) through a filter to remove something unwanted
They've begun filtering their water to remove impurities.
b
: to remove (something unwanted) by using a filter
a device that filters impurities from water
sunglasses that filter ultraviolet light
—often + outsunglasses that filter out ultraviolet light
—often used figurativelyThe purpose of the first interview is to filter out people who are not good candidates for the job.
2
always followed by an adverb or preposition
a
: to move through or into something in small amounts or in a gradual way
Sunlight filtered through the leaves.
His ideas have filtered down to his children.
b
: to come or go slowly in small groups or amounts
The crowd filtered into the arena.
The crowd filtered out (of the arena).
Early election returns have begun to filter in.
Cite this Entry
“Filter.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/filter. Accessed 19 Jun. 2026.
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