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.

---

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

---

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

One of Sentinel-3C's most important instruments, its synthetic aperture radar altimeter, is designed to measure the height of the ocean surface with high precision.

From Science Daily ● Oct. 12, 2026

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

From Barron's ● Sep. 9, 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

ASML’s more advanced high numerical aperture EUV systems face stitching and design constraints that are slowing adoption from customers, Scemama notes.

From The Wall Street Journal ● May 7, 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

Multi-layer soft materials first generate a rough mechanical conformation to the substrate, reducing leaking apertures to just micrometres.

From Science Daily ● Apr. 18, 2024

Despite the collection of doors and apertures in the set, the actors’ bodies inhabit it in limited ways.

From New York Times ● Sep. 19, 2022

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

Random Word

Spin the wheel and learn a new word!

---