What does aperture mean?
An aperture is an opening — a hole, gap, or passage through which something may enter, exit, or be seen. The word applies broadly, from the slits of ancient fortifications to the pores of living tissue, but it carries particular weight in optical science. In photography, the aperture is the adjustable diaphragm within a lens that governs how much light reaches the sensor, expressed as an f-number such as f/2.8 or f/16; photographers manipulate it both to control exposure and to shape depth of field. In astronomy, a telescope's aperture refers to the diameter of its primary mirror or lens, the key measure of its light-gathering power. Derived from Latin roots meaning 'to open', the word has a precise, slightly formal character, yet it appears comfortably in everyday speech whenever an opening needs describing. Its versatility across physics, art, and common usage makes it one of those rare words equally at home in an engineer's notebook and a poet's line.
nounAn opening, gap, or hole through which something can pass or be seen; in optics and photography, the opening in a lens that admits light to a camera's sensor or film.
- A physical opening, hole, or gap in a surface or structure.
- In photography and optics: the adjustable opening in a lens that controls how much light passes through.
- In astronomy: the diameter of the main light-gathering element (mirror or lens) of a telescope.
"The photographer widened the aperture to let more light into the lens."
"Light streamed through the narrow aperture of the medieval arrow slit."
"She set her camera to f/2.8, choosing a wide aperture to blur the background."
Standard plural; used when referring to multiple openings or to different aperture settings on lenses or instruments.
"The camera body offers apertures ranging from f/1.4 to f/22."
The word 'aperture' comes from the Latin for 'to open' — the same root that gives us 'overture' and 'discover', all about revealing what lies beyond.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of aperture
Aperture entered English in the early seventeenth century, borrowed from Latin 'apertura', meaning an opening, itself formed from 'aperire', 'to open'. This Latin verb also underlies English words such as 'overture', from Old French, and related forms like 'perforate'. The term was adopted into scientific vocabulary as optics and instrumentation advanced, giving it its enduring technical senses in photography and astronomy alongside its literal meaning of any opening.
How aperture is actually used
Neutral register — used in technical contexts (optics, photography, astronomy) as well as everyday descriptions of openings. In photography, 'aperture' specifically refers to the diaphragm setting, often described with f-numbers.
Easily confused with aperture
An aperient is a laxative substance that opens the bowels, while an aperture is simply an opening or hole.
An aperitif is an alcoholic drink served before a meal to stimulate the appetite, whereas an aperture is an opening or hole.