aperture

American  

[ap-er-cher] / ˈæp ər tʃər /

noun

• apertures
  plural

1. 

   an opening, as a hole, slit, crack, gap, etc.

2. Also called aperture stop. Optics. an opening, usually circular, that limits the quantity of light that can enter an optical instrument.

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aperture British  

/ ˈæpətʃə /

noun

1. a hole, gap, crack, slit, or other opening

2. physics

   1. a usually circular and often variable opening in an optical instrument or device that controls the quantity of radiation entering or leaving it

   2. the diameter of such an opening See also relative aperture

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Other Word Forms

Derived Forms

• apertural
  adjective
• apertured
  adjective

Inflected Forms

Nouns

• apertures
  plural

Etymology

Origin of aperture

1400–50; late Middle English < Latin apertūra an opening, equivalent to apert ( us ) opened (past participle of aperīre; aper ( i )- ( see aperient) + -tus past participle suffix) + -ūra -ure

Explanation

An aperture is an opening, usually a small one. “If you can thread the silk through that aperture and pull it out the other side, we can knot it and create a loop.” The most common place you’ll find aperture is when you’re talking about cameras or photography. In that case, an aperture refers specifically to the hole or opening in the lens that lets light through, which you can adjust (with the f-stop) to let in more or less light, resulting in a shallow or deep range of focus. A large aperture means only one tiny point of the photo will be in sharp focus, while a small aperture means that much of the background as well as the foreground will be in focus.

Example Sentences

See Examples For:

aperture apertures

They will come with an improved camera that allows users to adjust the lens aperture.

From Barron's ● Sep. 9, 2026

“We are going to look at opening up the aperture on how we acquire those customers, including possibly free offerings,” he said.

From The Wall Street Journal ● Aug. 25, 2026

But there was, indeed, a brief aperture of time in the pressure cooker of 2020 when it all seemed possible.

From Slate ● Aug. 17, 2026

Synthetic aperture radar operates by transmitting microwave pulses from a moving satellite or aircraft toward Earth's surface and then combining the returning signals into detailed images.

From Science Daily ● Jun. 12, 2026

“There’s a new one here!” the woman called Frau Mikes called through the aperture.

From "The Hiding Place" by Corrie ten Boom

To open it up to the street, the architects chose the motif of “frames, apertures and doorways.”

From The Wall Street Journal ● Dec. 17, 2025

Fractions of a second count and he can change apertures and focuses with a flick of his finger without taking his eyes from his quarry.

From BBC ● Aug. 4, 2024

Only when approaching the smallest apertures, which were half a wingspan wide, would the birds automatically resort to the tuck and glide, even though they were unfamiliar with the setup.

From Science Daily ● Nov. 9, 2023

When they did, these apertures warped the doughnut shape or caused the ring to wobble, the team reported.

From New York Times ● Mar. 21, 2023

Also, the bedroom has several valve apertures in its canvas.

From "The Martian" by Andy Weir