illusion

American  

[ih-loo-zhuhn] / ɪˈlu ʒən /

noun

illusions plural

1. something that deceives by producing a false or misleading impression of reality.

   Synonyms:

   chimera, fantasy, aberration

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.

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illusion British  

/ 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

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Synonym Usage

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.

Other Word Forms

Derived Forms

• illusionary
  adjective
• illusioned
  adjective

Inflected Forms

Nouns

• illusions
  plural

Etymology

Origin of illusion

First recorded in 1300–50; Middle English from 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) + -iōn- -ion

Explanation

An illusion is something that isn't real. It may look real, but it's actually fake — just a crafty construction or fantasy. Like the old rabbit-out-of-the-hat trick practiced by magicians around the globe. An illusion is an act of deception. Some optical illusions are pretty cool to watch, but an illusion can also point to an erroneous belief or false perception of reality, which is where you start getting into hallucination territory — seeing things that aren't there. You can give the illusion that you’re fascinated by your professor’s lecture by chewing on your pencil, furrowing your brow, and making sure to nod enthusiastically every so often.

Example Sentences

See Examples For:

illusion illusions

"I don't think anybody is under any illusion about the financial challenges we're all facing these days - there are requirements to cut back and to freeze funding," he warned.

From BBC ● Jul. 20, 2026

“AI-related stocks have been carrying the major indexes, creating the illusion of a calm market. But beneath the surface, conditions have been far more volatile,” Kramer said.

From MarketWatch ● Jul. 16, 2026

This carefully engineered system creates the illusion of ultrafast rotation, reaching effective rotational speeds far beyond what conventional mechanical systems can achieve.

From Science Daily ● Jul. 12, 2026

Lee’s standout identity plays — “Straight White Men,” “The Shipment” and “Songs of the Dragons Flying to Heaven” — reject the illusion of stable, coherent characters propagated by psychological realism.

From Los Angeles Times ● Jun. 29, 2026

The face one shows him he invariably reflects back at one, creating the illusion of warmth and depth when in fact he is brittle and shallow as a mirror.

From "The Secret History" by Donna Tartt

"He would never do that, let's not have any illusions," said Tikhanovskaya, who recently returned from a trip to Kyiv.

From Barron's ● Jun. 26, 2026

That’s an excellent summary to burst French illusions.

From The Wall Street Journal ● Jun. 12, 2026

"I'm under no illusions that Flora will present a very tough challenge, she's undefeated as a professional and has a good amateur pedigree so I have the utmost respect for her," added Taylor.

From BBC ● Jun. 5, 2026

Put simply, physics appears to allow the possibility that our memories are not reliable records but instead detailed illusions produced by chance.

From Science Daily ● May 3, 2026

Tyrion had no illusions where his own men were concerned.

From "A Clash of Kings" by George R.R. Martin

Related Words

• confusion
• deception
• delusion
• fantasy
• hallucination
• image
• misconception
• myth
• pipe dream
• semblance