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

• 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

The main camera has a 48MP sensor with quad pixel binning, an aperture of f/1.7, and an 82-degree field of view (FoV). —PC Magazine, 20 Aug. 2025

The series’ most recent season, however, sees its aperture widen, introducing more members of the big-wave community and traveling to multiple destinations beyond Nazaré, something the creators hadn’t really done before. —Trey Williams, HollywoodReporter, 20 Aug. 2025

The Pura 80 Ultra features a large 1-inch sensor, variable aperture, and dual-periscope zoom system, delivering superior image quality. —Paul Monckton, Forbes.com, 18 Aug. 2025

Viewing the rocky world through a telescope with an aperture of 4 inches or more under good atmospheric conditions may reveal Mercury's moon-like phases. —Anthony Wood, Space.com, 18 Aug. 2025

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