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
• perforation

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

Onboard Biomass is a P-band synthetic aperture radar (SAR) instrument. —Julian Dossett, Space.com, 12 May 2025

The latest model corrects course by doubling the laser aperture and more than halving the time necessary to get those same collagen-boosting benefits. —Justin Fenner, Robb Report, 12 May 2025

What’s The Best Way To Photograph The Northern Lights? With a regular camera, a wide-angle lens, an aperture or F-stop of four or less and a focus set to the furthest possible setting are recommended for capturing the northern lights, photography experts told National Geographic. —Ty Roush, Forbes.com, 9 May 2025

To get granular data, the researchers behind the new study turned to interferometric synthetic aperture radar (InSAR) measurements taken from satellites. —Andrea Thompson, Scientific American, 8 May 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