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optical illusion

noun
1.
See under illusion (def 4).
Origin
1785-1795
1785-95

illusion

[ih-loo-zhuh n] /ɪˈlu ʒən/
noun
1.
something that deceives by producing a false or misleading impression of reality.
2.
the state or condition of being deceived; misapprehension.
3.
an instance of being deceived.
4.
Psychology. a perception, as of visual stimuli (optical illusion) that represents what is perceived in a way different from the way it is in reality.
5.
a very thin, delicate tulle of silk or nylon having a cobwebbed appearance, for trimmings, veilings, and the like.
6.
Obsolete. the act of deceiving; deception; delusion.
Origin
1300-50; Middle English < Latin illūsiōn- (stem of illūsiō) irony, mocking, equivalent to illūs(us) past participle of illūdere to mock, ridicule (il- il-1 + lūd- play (see ludicrous) + -tus past participle suffix, with dt > s) + -iōn- -ion
Related forms
illusioned, adjective
Can be confused
allusion, delusion, elusion, hallucination, illusion (see synonym study at the current entry)
Synonyms
1. aberration, fantasy, chimera. illusion, hallucination, delusion refer to false perceptions or ideas. An illusion is a false mental image produced by misinterpretation of things that actually exist: A mirage is an illusion produced by reflection of light against the sky. A hallucination is a perception of a thing or quality that has no physical counterpart: Under the influence of LSD, Terry had hallucinations that the living-room floor was rippling. A delusion is a persistent false belief: A paranoiac has delusions of persecution.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples for optical illusion
  • Since a rainbow is an optical illusion, it doesn't have an actual endpoint.
  • Few know that this is not reality, but an optical illusion.
  • Some experts, however, say the ring may be nothing more than a kind of optical illusion.
  • There are quite a few other locations around the globe where a similar optical illusion has created the same impression.
  • Cynicism about the regime's intentions is so entrenched that few observers see this as more than an optical illusion.
  • The narrator is not sure if this actually happened, or if it was an optical illusion.
  • No mere optical illusion, it was an existential revelation that would inspire his later scientific work.
  • Mismatched panels create an optical illusion on this dress.
  • The distortion of the galaxy on the upper left is real, but the distortion on the galaxy at the right is an optical illusion.
  • But that is largely an optical illusion, reinforced by an antiquated national accounting system.
British Dictionary definitions for optical illusion

optical illusion

noun
1.
an object causing a false visual impression
2.
an instance of deception by such an object

illusion

/ɪˈluːʒən/
noun
1.
a false appearance or deceptive impression of reality the mirror gives an illusion of depth
2.
a false or misleading perception or belief; delusion he has the illusion that he is really clever
3.
(psychol) a perception that is not true to reality, having been altered subjectively in some way in the mind of the perceiver See also hallucination
4.
a very fine gauze or tulle used for trimmings, veils, etc
Derived Forms
illusionary, illusional, adjective
illusioned, adjective
Word Origin
C14: from Latin illūsiō deceit, from illūdere; see illude
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 optical illusion
illusion
mid-14c., "act of deception," from O.Fr. illusion "a mocking," from L. illusionem (nom. illusio) "a mocking, jesting, irony," from illudere "mock at," lit. "to play with," from in- "at" + ludere "to play" (see ludicrous). Sense of "deceptive appearance" developed in Eng. late 14c.
Online Etymology Dictionary, © 2010 Douglas Harper
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optical illusion in Medicine

illusion il·lu·sion (ĭ-lōō'zhən)
n.

  1. An erroneous perception of reality.

  2. An erroneous concept or belief.

  3. The condition of being deceived by a false perception or belief.

  4. Something, such as a fantastic plan or desire, that causes an erroneous belief or perception.


il·lu'sion·al or il·lu'sion·ar'y (-zhə-něr'ē) 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 optical illusion

illusion

a misrepresentation of a "real" sensory stimulus-that is, an interpretation that contradicts objective "reality" as defined by general agreement. For example, a child who perceives tree branches at night as if they are goblins may be said to be having an illusion. An illusion is distinguished from a hallucination, an experience that seems to originate without an external source of stimulation. Neither experience is necessarily a sign of psychiatric disturbance, and both are regularly and consistently reported by virtually everyone.

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