ap·er·ture | \ ˈa-pər-ˌchu̇r , ˈa-pə- , -chər , -ˌtyu̇r , -ˌtu̇r \

Definition of aperture 

1 : an opening or open space : hole entered the cave through a narrow aperture

2a : 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

Keep scrolling for more

Synonyms for aperture


hole, opening, orifice, perforation

Visit the Thesaurus for More 

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

In exchange for the zoom, the camera’s aperture is changing from f/1.8-2.8 to the somewhat slower f/2.8-4.5. Jacob Kastrenakes, The Verge, "Sony’s RX100 VI adds a long zoom lens to the best compact camera," 5 June 2018 Then, set the aperture on the lens nice and wide — an F-stop of about 1.4 — to let more light hit the camera’s sensor. Rachel Becker, The Verge, "How to capture the eerie nighttime clouds of climate change," 6 July 2018 Also new to the camera is a super bright mode that detects when a scene is too dark for the normal aperture and automatically increases the brightness digitally to capture more detail. Michael Simon, PCWorld, "LG unveils the G7 ThinQ with more screen and an AI-infused camera," 2 May 2018 Four concrete hollow cylinders — each 18 feet long and 9 feet in diameter and perforated with a constellation of small apertures emitting patterns of light inside the tube — are arranged in the landscape in an open cross. Hilarie M. Sheets, New York Times, "Dia Acquires ‘Sun Tunnels,’ Its First Piece of Land Art by a Woman," 7 Mar. 2018 The Cloud-Aerosol Transport System, or CATS, instrument was designed to study the atmosphere using a laser firing through a large aperture door. William Harwood, CBS News, "Space station astronauts take spacewalk to install cameras," 14 June 2018 More from Michael Clevenger: Flying high inside an aerobatic Thunder Over Louisville plane before the air show The best photos will always be crafted on the framework of ISO, shutter speed, and aperture because those are inherent in every photo. Michael Clevenger, The Courier-Journal, "Courier Journal photographer gambled on Triple Crown shots – and won," 15 June 2018 Tra rilanci del Manchester City e piccole aperture del Napoli si sta arrivando alla cifra giusta per sbloccare definitivamente il trasferimento di Jorginho: 55 milioni. SI.com, "Man City Eye Southampton & Real Madrid Midfielders as Alternatives as Jorginho Negotiations Stall," 6 June 2018 Forgive me for not being bowled over by a camera with a mechanical aperture. Joanna Stern, WSJ, "We Were Promised Mind-Blowing Personal Tech. What’s the Hold-Up?," 3 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'aperture.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of aperture

15th century, in the meaning defined at sense 1

History and Etymology for aperture

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

Keep scrolling for more

Learn More about aperture

Statistics for aperture

Last Updated

13 Sep 2018

Look-up Popularity

Time Traveler for aperture

The first known use of aperture was in the 15th century

See more words from the same century

Keep scrolling for more

More Definitions for aperture



English Language Learners Definition of aperture

: a hole or small opening in something

: an opening that controls the amount of light that passes through a lens (such as a camera lens)


ap·er·ture | \ ˈa-pər-ˌchu̇r \

Kids Definition of aperture

: an opening or open space : hole


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

Medical Definition of aperture 

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

Keep scrolling for more

Comments on aperture

What made you want to look up aperture? Please tell us where you read or heard it (including the quote, if possible).


alleviating pain or harshness

Get Word of the Day daily email!

Test Your Vocabulary

Musical Words Quiz

  • gramophone
  • Which word describes a musical performance marked by the absence of instrumental accompaniment?
Spell It

Can you spell these 10 commonly misspelled words?


Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!