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.
Origin of aperture
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a hole, gap, crack, slit, or other opening
- a usually circular and often variable opening in an optical instrument or device that controls the quantity of radiation entering or leaving it
- 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
early 15c., from Latin apertura "an opening," from apertus, past participle of aperire "to open" (see overt).
Online Etymology Dictionary, © 2010 Douglas Harper
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.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.