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

Over the next several days, Roman's high-gain antenna and visor-like deployable aperture cover will also deploy.

From Science Daily ● Aug. 31, 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

In the video’s limited aperture, Gamble’s arrest alongside a suburban highway could have been anywhere.

From Slate ● May 4, 2026

The dish, one of the most distinctive landmarks on the Fairbanks skyline, had been erected to collect data from satellites equipped with synthetic aperture radar of Walt McCandless’s design.

From "Into the Wild" by Jon Krakauer

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

There are pinholes in the murk, apertures such as the Instagram feeds of Gaza photographers and a small number of testimonies that slip through.

From New York Times ● Jan. 30, 2024

Dudley hopes to conduct further experiments, perhaps with a sequence of different apertures, to determine how birds navigate multiple obstacles.

From Science Daily ● Nov. 9, 2023

The next three weeks were a honeycomb of determination with apertures for the days to go in and out.

From "I Know Why the Caged Bird Sings" by Maya Angelou