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

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

The analyst also points to rising competitive pressure, with one rival now selling sonar systems independently and customers questioning the “cost of synthetic aperture sonar relative to the rapidly falling costs of autonomous vessels.”

From The Wall Street Journal ● May 29, 2026

The 2025/26 away kit, manufactured by sportswear firm Hummel, features a repeating geometric pattern showing the lighthouse, viewed through a circular design resembling the sculpture's aperture.

From BBC ● Apr. 24, 2026

He brought out Kehlani for “Folded,” another perfectly regal ballad that revels in a small aperture.

From Los Angeles Times ● Apr. 13, 2026

Tally popped open the heart pendant, looking down into the little glowing aperture where the laser waited to read her eye- print.

From "Uglies" by Scott Westerfeld

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

Other than this there were no openings or apertures through which light could seep.

From "Snow Falling on Cedars: A Novel" by David Guterson