aperture
noun
ap·er·ture
ˈa-pər-ˌchu̇r 
ˈa-pə-,
-chər,
-ˌtyu̇r,
-ˌtu̇r
1
: an opening or open space : hole
entered the cave through a narrow aperture
2
a
: the opening in a photographic lens that admits the light
b
: the diameter of the stop in an optical system that determines the diameter of the bundle of rays traversing the instrument
c
: the diameter of the objective lens or mirror of a telescope
Examples of aperture in a Sentence
We entered the cave through a narrow aperture.
The photograph was taken using a fast shutter speed and a large aperture.
Recent Examples on the Web
Observing the planet through a telescope with an aperture of 4 inches or more under dark sky conditions will reveal the moon-like phases of the distant world, though utmost care must be taken to ensure that the sun is safely below the horizon before pointing telescopic equipment in its direction.
—
Anthony Wood, Space.com, 29 Oct. 2025
Capella Space, Umbra, and ICEYE provide synthetic aperture radar satellites commercially—another improbability is that there is not just one but multiple commercial SAR companies in the world.
—Literary Hub, 28 Oct. 2025
At its center, the lens scores in the outstanding range at its maximum aperture (5,700 lines), though its edges and corners aren't as clear and bring the average score down into the excellent range for a 60MP chip (4,400 lines).
—PC Magazine, 12 Oct. 2025
In Mint, Regan has widened the aperture and secured a buzzy cast, including a rare TV acting performance from Ben Coyle-Larner AKA hip-hop star Loyle Carner.
—Jesse Whittock, Deadline, 8 Oct. 2025
See All Example Sentences for aperture
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Anthony Wood, Space.com, 29 Oct. 2025
Capella Space, Umbra, and ICEYE provide synthetic aperture radar satellites commercially—another improbability is that there is not just one but multiple commercial SAR companies in the world.
—Literary Hub, 28 Oct. 2025
At its center, the lens scores in the outstanding range at its maximum aperture (5,700 lines), though its edges and corners aren't as clear and bring the average score down into the excellent range for a 60MP chip (4,400 lines).
—PC Magazine, 12 Oct. 2025
In Mint, Regan has widened the aperture and secured a buzzy cast, including a rare TV acting performance from Ben Coyle-Larner AKA hip-hop star Loyle Carner.
—Jesse Whittock, Deadline, 8 Oct. 2025
See All Example Sentences for aperture
Cite this Entry
“Aperture.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/aperture. Accessed 31 Oct. 2025.
Copy CitationKids Definition
aperture
noun
ap·er·ture
ˈap-ə(r)-ˌchu̇(ə)r
-chər
1
: an opening or open space : hole
2
a
: the opening in a camera lens that allows light through
b
: the diameter of the opening in a camera lens
Medical Definition
aperture
noun
ap·er·ture
ˈap-ə(r)-ˌchu̇(ə)r, -chər, -ˌt(y)u̇(ə)r
1
: an opening or open space
2
: the diameter of the stop in an optical system that determines the diameter of the bundle of rays traversing the instrument
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