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misinterpretation of things that exist: A mirage is an illusion caused by atmospheric conditions.
Not to be confused with:
delusion – a persistent false belief: A paranoiac has delusions of persecution.
Abused, Confused, & Misused Words by Mary Embree Copyright © 2007, 2013 by Mary Embree
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a. An erroneous perception of reality: Mirrors gave the illusion of spaciousness.
b. An erroneous concept or belief: The notion that money can buy happiness is an illusion.
2. The condition of being deceived by a false perception or belief: spent months flailing about in illusion.
3. Something that is erroneously perceived or construed: The animal in the shadows turned out to be an illusion.
4. A fine transparent net fabric, used for dresses or trimmings.

[Middle English illusioun, from Old French, from Late Latin illūsiō, illūsiōn-, from Latin, a mocking, irony, from illūsus, past participle of illūdere, to mock : in-, against; see in-2 + lūdere, to play; see leid- in Indo-European roots.]

il·lu′sion·al, il·lu′sion·ar′y (-zhə-nĕr′ē) adj.
il·lu′sion·less adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


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. (Psychology) 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. (Textiles) a very fine gauze or tulle used for trimmings, veils, etc
[C14: from Latin illūsiō deceit, from illūdere; see illude]
ilˈlusionary, ilˈlusional adj
ilˈlusioned adj
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ɪˈlu ʒən)

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. 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 delicate tulle of silk or nylon having a cobwebbed appearance, for trimmings, veilings, and the like.
6. Obs. the act of deceiving.
[1300–50; Middle English < Latin illūsiō irony, mocking, derivative of illūdere to mock, ridicule =-il -il1 + lūdere to play]
il•lu′sion•al, il•lu′sion•ar`y, adj.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.


 of painters: group of painters, 15th century.
Dictionary of Collective Nouns and Group Terms. Copyright 2008 The Gale Group, Inc. All rights reserved.



Barmecide feast An illusion of plenty; any illusion. In The Arabian Nights, Barmecide, a wealthy Persian noble, invited the beggar Schacabac to dine with him at a banquet table laden with dishes, all empty of food. The host feigned indulgence in the illusionary banquet, and when the beggar followed suit with gusto, Barmecide repented of his joke and served the pauper a sumptuous repast. This latter aspect of the story does not figure into the meaning of the phrase; Barmecide feast retains only that aspect of the story dealing with the nonexistent fare.

cast beyond the moon To indulge in fanciful, outlandish thoughts about the future; to imagine the impossible. One definition of cast is “to calculate or conjecture, to anticipate, to forecast” (OED). The moon was considered a mysterious force of inexplicable power. Beyond the moon reinforces the idea of a realm where nothing is impossible. The phrase appeared as early as the mid-16th century.

But oh, I talk of things impossible, and cast beyond the moon. (Thomas Hey wood, A Woman Killed with Kindness, 1607)

castles in Spain Fanciful notion; pipe dream—the opposite of all that is practical, reasonable, and grounded in common sense. The phrase appeared in English in The Romance of the Rose (approx. 1400).

Thou shalt make castles then in Spain,
And dream of joy, all but in vain.

Château en Espagne, the French equivalent, dates from the 13th century. The OED attributes the reference to Spain to the fact that it represents a “foreign country where one had no standing-ground.” Spain was superseded by the now current air or sky.

castles in the air Visionary projects; daydreams or fantasies; impractical, romantic, or whimsical schemes; half-baked ideas without solid foundation. This phrase, common since 1575, is equivalent to castles in the sky.

Things are thought, which never yet were wrought,

And castles built above in lofty skies.

(George Gascoigne, The Steele Glas, 1575)

Fata Morgana See ENTICEMENT.

fool’s paradise A self-deceptive state of contentment or bliss; a mental condition in which one’s happiness is generated by delusions and false hopes. The expression is derived from the Latin limbus fatuorum, a quasi-limbo where the mentally feeble went after death. The phrase has evolved to mean the fantasy world inhabited by certain daft individuals.

You have been revelling in a fool’s paradise of leisure. (James Beres-ford, The Miseries of Human Life, 1807)

pie in the sky An illusion of future benefits and blessings which will never be realized; an unattainable state of happiness or utopia. This expression, probably alluding to the concept of pie as something sweet and desirable, and sky as in the air, beyond one’s reach, was popularized in a World War I song often attributed to Joe Hill (1927):

You will eat, bye and bye,
In the glorious land above the sky!
Work and pray,
Live on hay,
You’ll get pie in the sky when you die!

pipe dream An unrealistic and often fantastic plan, goal, or idea. One source suggests that this expression alludes to the dreams and schemes which may inspire an opium addict after he has smoked a pipeful of the drug.

tilt at windmills To combat imaginary evils, to fight opponents or injustices that are merely the figments of an over-active imagination. The allusion is to Cervantes’ Don Quixote de la Mancha, in which the hero Don Quixote imagines the windmills he has come upon to be giants and proceeds to do battle, with the result that both the knight and his horse are injured and his lance destroyed. At this Quixote’s squire Sancho Panza says that anyone who mistakes windmills for giants must have windmills in his head, i.e., suffer delusions, be crazy. The equivalent French phrase is se battre contre les moulins à vent. A variant of the expression appeared in Frederic W. Farrar’s book on Christ:

Dr. Edersheim is again—so far as I am concerned—fighting a windmill.

Picturesque Expressions: A Thematic Dictionary, 1st Edition. © 1980 The Gale Group, Inc. All rights reserved.



You can use either of these words to say that someone has a wrong belief.

They have the illusion that every contingency can be worked out in advance.
One patient had the delusion that he was Trotsky.

You say that someone is under an illusion or delusion.

Finally, I think he wanted me because he was under the illusion that I was loaded with money.
I still laboured under the nice middle-class delusion that everyone was a good guy at heart.

You can also say that someone suffers from an illusion or delusion.

A man who has had a leg amputated often suffers from the delusion that the leg is still there.

If you have an illusion of something, you believe that it exists when in fact it does not.

We have an illusion of freedom.
In return they are allowed the illusion of a guiltless life.
1. another meaning of 'illusion'

An illusion is also something that looks or sounds like one thing, but is either something else or is not there at all.

It might be an optical illusion but he actually seems to lift some horses in races when they are tired.
I fancy I can hear her voice, but that must be an illusion.

You do not use delusion with this meaning.

Collins COBUILD English Usage © HarperCollins Publishers 1992, 2004, 2011, 2012
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.illusion - an erroneous mental representationillusion - an erroneous mental representation  
fantasm, phantasm, phantasma, phantom, shadow, apparition - something existing in perception only; "a ghostly apparition at midnight"
appearance - a mental representation; "I tried to describe his appearance to the police"
irradiation - the apparent enlargement of a bright object when viewed against a dark background
phantom limb - the illusion that a limb still exists after it has been amputated
2.illusion - something many people believe that is falseillusion - something many people believe that is false; "they have the illusion that I am very wealthy"
misconception - an incorrect conception
bubble - an impracticable and illusory idea; "he didn't want to burst the newcomer's bubble"
ignis fatuus, will-o'-the-wisp - an illusion that misleads
wishful thinking - the illusion that what you wish for is actually true
3.illusion - the act of deluding; deception by creating illusory ideas
dissimulation, deception, dissembling, deceit - the act of deceiving
4.illusion - an illusory featillusion - an illusory feat; considered magical by naive observers
performance - the act of presenting a play or a piece of music or other entertainment; "we congratulated him on his performance at the rehearsal"; "an inspired performance of Mozart's C minor concerto"
card trick - a trick performed with playing cards
prestidigitation, sleight of hand - manual dexterity in the execution of tricks
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.


1. delusion, misconception, misapprehension, fancy, deception, fallacy, self-deception, false impression, false belief, misbelief No one really has any illusions about winning the war.
2. false impression, feeling, appearance, impression, fancy, deception, imitation, sham, pretence, semblance, fallacy Floor-to-ceiling windows give the illusion of extra space.
false impression fact, truth, reality, actuality
3. fantasy, vision, hallucination, trick, spectre, mirage, semblance, daydream, apparition, chimera, figment of the imagination, phantasm, ignis fatuus, will-o'-the-wisp It creates the illusion of moving around in the computer's graphic environment.
Collins Thesaurus of the English Language – Complete and Unabridged 2nd Edition. 2002 © HarperCollins Publishers 1995, 2002


1. An erroneous perception of reality:
2. An illusory mental image:
3. A fantastic, impracticable plan or desire:
The American Heritage® Roget's Thesaurus. Copyright © 2013, 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
وَهْمٌوَهْم، صورة خادِعَه
tálmynd, tálsÿn
göz aldanmasıhayalî görüntüyanılsama
ảo tưởng


[ɪˈluːʒən] N
1. (= deceptive appearance) → ilusión f
optical illusionilusión f óptica
it gives an illusion of spacecrea una ilusión or impresión de espacio
2. (= misapprehension) → ilusión f
to be under an illusionhacerse falsas ilusiones, estar en un error
I am under no illusions on that scoresobre ese punto no me hago (falsas) ilusiones
to be under the illusion thatcreerse que ...
he was under the illusion that he would winse creía que iba a ganar
he cherishes the illusion thatabriga la esperanza de que ... + subjun
Collins Spanish Dictionary - Complete and Unabridged 8th Edition 2005 © William Collins Sons & Co. Ltd. 1971, 1988 © HarperCollins Publishers 1992, 1993, 1996, 1997, 2000, 2003, 2005


[ɪˈluːʒən] nillusion f
to be under the illusion that ... → nourrir l'illusion que ...
to have no illusions about sth → ne se faire aucune illusion sur qch
Nobody has any illusions about winning the war → Personne ne se fait aucune illusion sur l'issue favorable de la guerre.
to give the illusion of sth (= impression) → donner l'illusion de qch
Collins English/French Electronic Resource. © HarperCollins Publishers 2005


nIllusion f; (= hope also)trügerische Hoffnung; (= misperception)Täuschung f; to be under an illusioneiner Täuschung (dat)unterliegen, sich (dat)Illusionen machen; to be under the illusion that …sich (dat)einbilden, dass …; to be under or have no illusionssich (dat)keine Illusionen machen, sich (dat)nichts vormachen (→ about über +acc); no one has any illusions about winning the warniemand macht sich Illusionen, dass der Krieg gewonnen werden kann; it gives the illusion of spacees vermittelt die Illusion von räumlicher Weite; a tan can give the illusion of being slimmerwenn man braun ist, kann das den Eindruck erwecken, dass man schlanker ist ? optical illusion
Collins German Dictionary – Complete and Unabridged 7th Edition 2005. © William Collins Sons & Co. Ltd. 1980 © HarperCollins Publishers 1991, 1997, 1999, 2004, 2005, 2007


[ɪˈluːʒn] nillusione f
to be under an illusion → illudersi
to be under the illusion that → illudersi che
to have no illusions → non farsi illusioni
Collins Italian Dictionary 1st Edition © HarperCollins Publishers 1995


(iˈluːʒən) noun
(something that produces) a false impression, idea or belief. an optical illusion.
ilˈlusionist noun
a conjuror.
Kernerman English Multilingual Dictionary © 2006-2013 K Dictionaries Ltd.


وَهْمٌ iluze illusion Illusion παραίσθηση ilusión illuusio illusion iluzija illusione 錯覚 환각 illusie illusjon iluzja ilusão иллюзия illusion ภาพลวงตา yanılsama ảo tưởng 幻想
Multilingual Translator © HarperCollins Publishers 2009


n. ilusión, interpretación imaginaria de impresiones sensoriales.
English-Spanish Medical Dictionary © Farlex 2012


n ilusión f
English-Spanish/Spanish-English Medical Dictionary Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
References in classic literature ?
Plenty of these rooms have been seen since, mainly at exhibitions: they are called "palaces of illusion," or some such name.
It is an illusion that youth is happy, an illusion of those who have lost it; but the young know they are wretched, for they are full of the truthless ideals which have been instilled into them, and each time they come in contact with the real they are bruised and wounded.
But the whole effect is spoiled when I look at them - at Tetralani, five feet ten in her stocking feet and weighing a hundred and ninety pounds, and at Barillo, a scant five feet four, greasy-featured, with the chest of a squat, undersized blacksmith, and at the pair of them, attitudinizing, clasping their breasts, flinging their arms in the air like demented creatures in an asylum; and when I am expected to accept all this as the faithful illusion of a love-scene between a slender and beautiful princess and a handsome, romantic, young prince - why, I can't accept it, that's all.
It is a feeling, a sentiment, a something based upon illusion and not a product of the intellect at all."
As to Karain, nothing could happen to him unless what happens to all--failure and death; but his quality was to appear clothed in the illusion of unavoidable success.
"I do want him to think I look well, and tell them so at home," said Amy to herself, as she put on Flo's old white silk ball dress, and covered it with a cloud of fresh illusion, out of which her white shoulders and golden head emerged with a most artistic effect.
As its holiest, it once loved "Thou-shalt": now is it forced to find illusion and arbitrariness even in the holiest things, that it may capture freedom from its love: the lion is needed for this capture.
Always to be finding the other an illusion, and going off and forgetting about them, never to be certain that you cared, or that he wasn't caring for some one not you at all, the horror of changing from one state to the other, being happy one moment and miserable the next--that's the reason why we can't possibly marry.
This time the illusion, or rather the reality, surpassed anything Valentine had before experienced; she began to believe herself really alive and awake, and the belief that her reason was this time not deceived made her shudder.
Baudoyer, Isidore The Middle Classes Cousin Pons Bianchon, Horace Father Goriot The Atheist's Mass Cesar Birotteau The Commission in Lunacy Lost Illusions A Distinguished Provincial at Paris A Bachelor's Establishment The Secrets of a Princess Pierrette A Study of Woman Scenes from a Courtesan's Life Honorine The Seamy Side of History The Magic Skin A Second Home A Prince of Bohemia Letters of Two Brides The Muse of the Department The Imaginary Mistress The Middle Classes Cousin Betty The Country Parson In addition, M.
It is when in this condition that he strips away the husks of life's healthiest illusions and gravely considers the iron collar of necessity welded about the neck of his soul.
"The trouble is," sighed the Doctor, grasping her meaning intuitively, "that youth is given up to illusions. It seems to be a provision of Nature; a decoy to secure mothers for the race.