aperture

noun

ap·​er·​ture ˈa-pər-ˌchu̇r 

ˈa-pə-, 

-chər, 

-ˌtyu̇r, 

-ˌtu̇r

1

: an opening or open space : hole

entered the cave through a narrow aperture

2

a

: the opening in a photographic lens that admits the light

b

: the diameter of the stop in an optical system that determines the diameter of the bundle of rays traversing the instrument

c

: the diameter of the objective lens or mirror of a telescope

Synonyms of aperture

• hole
• opening
• orifice
• crevice
• slit

Examples of aperture in a Sentence

We entered the cave through a narrow aperture.

The photograph was taken using a fast shutter speed and a large aperture.

Recent Examples on the Web

How Variable Aperture Changes iPhone Photography Variable-aperture lenses change the size of the lens opening, which has major implications in terms of length of exposure and, therefore, the depth of field of an image. —David Phelan, Forbes.com, 31 May 2026

Broadening the aperture means a wider universe of companies to fund, and protects against challenges in one technology or sector. —Justin Worland, Time, 28 May 2026

Along with a 50-megapixel main camera with autofocus and a F1/8 aperture is an ultra-wide actioncam built around a 1/2-inch-type IMX586 imaging sensor. —Paul Ridden may 17, New Atlas, 17 May 2026

Of course, the film quickly became a conduit for Harari’s own concerns, made all the more resonant once the narrative aperture widens to reveal that its central soul-swap may be only one of many. —Ben Croll, IndieWire, 15 May 2026

Word History

Etymology

Middle English, borrowed from Latin apertūra, from apertus, past participle of aperīre "to open" + -ūra -ure — more at aperient

First Known Use

15th century, in the meaning defined at sense 1

Kids Definition

aperture

noun

ap·​er·​ture ˈap-ə(r)-ˌchu̇(ə)r 

-chər

1

: an opening or open space : hole

2

a

: the opening in a camera lens that allows light through

b

: the diameter of the opening in a camera lens

Medical Definition

aperture

noun

ap·​er·​ture ˈap-ə(r)-ˌchu̇(ə)r, -chər, -ˌt(y)u̇(ə)r 

1

: an opening or open space

2

: the diameter of the stop in an optical system that determines the diameter of the bundle of rays traversing the instrument