aperture

American  

[ap-er-cher] / ˈæp ər tʃər /

noun

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

• apertural adjective
• apertured adjective

Etymology

Origin of aperture

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

Example Sentences

The outcome is a virtual synthetic aperture that is far larger than any individual sensor.

From Science Daily • Jan. 10, 2026

Narrator Jodie Foster widens the film’s aperture a bit early on, referring to the period “between Watergate and the Bicentennial” as the documentary’s focus.

From The Wall Street Journal • Dec. 18, 2025

A hermit crab will inspect a shell with care, running antennae and claws over its contours, before delicately lowering its rear end into the aperture.

From Slate • Aug. 19, 2025

"I learned how to shoot at night, adjust shutter speed and aperture," said Keerthi, who lives in the Tenkasi district.

From BBC • Mar. 14, 2025

He snapped the back of the camera shut and chose the appropriate shutter and aperture settings, which controlled the amount of light the film would be exposed to.

From "Shooting Kabul" by N. H. Senzai