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

Momentum breeds momentum: each successful float provides price discovery that the next issuer can cite, widening the aperture a little more. —Zennon Kapron, Forbes.com, 28 May 2025

Functionality: Focal range and fast maximum aperture aside, the 8-16mm features a manual aperture ring like many Fujifilm lenses. —James Abbott, Space.com, 27 May 2025

The phone has a 13MP ultra-wide camera with an f/2.2 aperture that can capture macro images. —PC Magazine, 18 May 2025

With that opposition in mind, bill sponsor Sen. Robert Rodriguez unveiled amendments to expand the proposal’s aperture before the vote Tuesday. —Nick Coltrain, Denver Post, 29 Apr. 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