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

Expanding the receiver aperture can improve results, but only up to a certain limit.

From Science Daily • Feb. 17, 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 camera’s aperture widens during filming to capture the full spectacle.

From Salon • Aug. 23, 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

Fischer then pointed to the camera aperture he’d complained about the previous day, and quickly left the stage with his clock running.

From "Endgame" by Frank Brady