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

Open the aperture beyond ROI, and leverage the return on experience (ROX) framework shared in my previous article to create a rather holistic set of metrics. —Sujay Saha, Forbes, 18 Dec. 2024

The 18-55mm's depth of field is quite slim when focusing close, even with the aperture stopped down. —PCMAG, 2 Dec. 2024

With a huge aperture that measures 13-feet in diameter, DKIST is the world’s largest solar telescope. —Laura Baisas, Popular Science, 3 Oct. 2024

It was spotted by a synthetic aperture radar (SAR) system equipped on a satellite. —Daniel R. Depetris, Newsweek, 6 Dec. 2024

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