an opening, as a hole, slit, crack, gap, etc.
Also called aperture stop. Optics. an opening, usually circular, that limits the quantity of light that can enter an optical instrument.

Nearby words

  1. apert,
  2. apert's syndrome,
  3. apert-crouzon syndrome,
  4. apertognathia,
  5. apertometer,
  6. aperture card,
  7. aperture priority,
  8. aperture ratio,
  9. aperture synthesis,
  10. aperture-priority

Origin of aperture

1400–50; late Middle English < Latin apertūra an opening, equivalent to apert(us) opened (past participle of aperīre; aper(i)- (see aperient) + -tus past participle suffix) + -ūra -ure

Related formsap·er·tur·al [ap-er-choo r-uh l] /ˈæp ərˌtʃʊər əl/, adjectiveap·er·tured, adjective

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for aperture

British Dictionary definitions for aperture



a hole, gap, crack, slit, or other opening
  1. a usually circular and often variable opening in an optical instrument or device that controls the quantity of radiation entering or leaving it
  2. the diameter of such an openingSee also relative aperture

Word Origin for aperture

C15: from Late Latin apertūra opening, from Latin aperīre to open

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for aperture



early 15c., from Latin apertura "an opening," from apertus, past participle of aperire "to open" (see overt).

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for aperture




An opening, such as a hole, gap, or slit.
A usually adjustable opening in an optical instrument, such as a microscope, a camera, or a telescope, that limits the amount of light passing through a lens or onto a mirror.
The diameter of such an opening.
The diameter of the objective of a telescope or microscope.
Related formsaper•tur′al adj.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.