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aperture

[ap-er-cher] /ˈæp ər tʃər/
noun
1.
an opening, as a hole, slit, crack, gap, etc.
2.
Also called aperture stop. Optics. an opening, usually circular, that limits the quantity of light that can enter an optical instrument.
Origin
late Middle English
1400-1450
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 forms
apertural
[ap-er-choo r-uh l] /ˈæp ərˌtʃʊər əl/ (Show IPA),
adjective
apertured, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for apertures
  • You'll get much better low-light shots with larger apertures.
  • They asked volunteers to describe how they perceived the motion of moving lines seen through apertures.
  • To measure a star's diameter, one increases the separation between the apertures until the fringes disappear.
  • It measured the light striking it and suggested a range of appropriate combinations of apertures and shutter speeds.
  • In order to get smaller feature size, small apertures have to be used to extract the beam and at the same time act as a mask.
  • Unfortunately, these apertures are usually not known in field applications.
British Dictionary definitions for apertures

aperture

/ˈæpətʃə/
noun
1.
a hole, gap, crack, slit, or other opening
2.
(physics)
  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 opening See also relative aperture
Word Origin
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
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Word Origin and History for apertures

aperture

n.

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

Online Etymology Dictionary, © 2010 Douglas Harper
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apertures in Medicine

aperture ap·er·ture (āp'ər-chər)
n.

  1. An opening, such as a hole, gap, or slit.

  2. 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.

  3. The diameter of such an opening.

  4. The diameter of the objective of a telescope or microscope.


ap'er·tur'al adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Encyclopedia Article for apertures

aperture

in optics, the maximum diameter of a light beam that can pass through an optical system. The size of an aperture is limited by the size of the mount holding the optical component, or the size of the diaphragm placed in the bundle of light rays. The hole in the mount or diaphragm that limits the size of the aperture is called an aperture stop. Thus, an aperture stop determines the amount of light that traverses an optical system and hence determines the image illumination

Learn more about aperture with a free trial on Britannica.com
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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