ap·er·ture

[ap-er-cher]
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:
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

ap·er·tur·al [ap-er-choor-uhl] , adjective
ap·er·tured, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2013.
Cite This Source Link To aperture
00:10
Aperture is always a great word to know.
So is gobo. Does it mean:
a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.
a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.
Collins
World English Dictionary
aperture (ˈæpətʃə) [Click for IPA pronunciation guide]
 
n
1.  a hole, gap, crack, slit, or other opening
2.  physics
 a.  a usually circular and often variable opening in an optical instrument or device that controls the quantity of radiation entering or leaving it
 b.  See also relative aperture the diameter of such an opening
 
[C15: from Late Latin apertūra opening, from Latin aperīre to open]

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Etymonline
Word Origin & History

aperture
1640s, from L. apertura "an opening," from apertus, pp. of aperire "to open" (see overt).
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

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 Britannica
Encyclopedia

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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Example sentences
The subcutaneous inguinal ring is seen as a distinct aperture only after the
  intercrural fascia has been removed.
It carries a 27-cm aperture telescope designed to detect tiny changes in
  brightness from nearby stars.
The iris is a circular diaphragm behind the cornea, and presents near its
  center a rounded aperture, the pupil.
Once your aperture gets much larger than that, you're averaging over lots of
  little blobs of air, which makes things worse.
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