Try Our Apps


Pore Over vs. Pour Over

optical illusion

See under illusion (def 4).
Origin of optical illusion


[ih-loo-zhuh n] /ɪˈlu ʒən/
something that deceives by producing a false or misleading impression of reality.
the state or condition of being deceived; misapprehension.
an instance of being deceived.
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.
a very thin, delicate tulle of silk or nylon having a cobwebbed appearance, for trimmings, veilings, and the like.
Obsolete. the act of deceiving; deception; delusion.
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)
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. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
Cite This Source
Examples from the Web for optical illusion
Contemporary Examples
Historical Examples
  • I didn't for a moment believe that Terry had "seen a ghost," or had an optical illusion.

    The Brightener C. N. Williamson
  • And yet we are asked to believe that all this is merely an optical illusion.

    Illogical Geology George McCready Price
  • The burning atmosphere, the motionless air caused doubtless the optical illusion.

    The Wave Algernon Blackwood
  • This is an optical illusion, but it serves the tracker's purpose.

    Tracks and Tracking Josef Brunner
  • But colour for colour's sake or optical illusion did not long hold him.

    Ivory Apes and Peacocks James Huneker
  • "Then it was an optical illusion, and I am going out of my mind," said Enid despairingly.

    A Life Sentence Adeline Sergeant
  • The rapid progressive motion sometimes assigned to them may be regarded as the natural result of an optical illusion.

  • An optical illusion is discovered in a single instance of the phenomenon.

  • "An optical illusion," answered Mary Grey, in a low, tremulous tone and with her face carefully kept in the shadow.

    Victor's Triumph Mrs. E. D. E. N. Southworth
British Dictionary definitions for optical illusion

optical illusion

an object causing a false visual impression
an instance of deception by such an object


a false appearance or deceptive impression of reality: the mirror gives an illusion of depth
a false or misleading perception or belief; delusion: he has the illusion that he is really clever
(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
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
Cite This Source
Word Origin and History for optical illusion



mid-14c., "act of deception," from Old French illusion "a mocking, deceit, deception" (12c.), from Latin illusionem (nominative illusio) "a mocking, jesting, irony," from illudere "mock at," literally "to play with," from assimilated form of in- "at, upon" (see in- (2)) + ludere "to play" (see ludicrous). Sense of "deceptive appearance" developed in Church Latin and was attested in English by late 14c. Related: Illusioned "full of illusions" (1920).

Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
optical illusion in Medicine

illusion il·lu·sion (ĭ-lōō'zhən)

  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.
Cite This Source

Word of the Day

Difficulty index for optical illusion

Few English speakers likely know this word

Word Value for optical

Scrabble Words With Friends