illusion

noun

il·​lu·​sion i-ˈlü-zhən 

plural illusions

1

a(1)

: a misleading image presented to the vision : optical illusion

a technique that creates the illusion of space

(2)

: something that deceives or misleads intellectually

the statements with their supposed profits were all an illusion

(3)

: an illusory effect created by a sleight-of-hand performer or a magician

b(1)

: perception of something objectively existing in such a way as to cause misinterpretation of its actual nature

(2)

: hallucination sense 1

(3)

: a pattern capable of reversible perspective

2

a(1)

: the state or fact of being intellectually deceived or misled : misapprehension

was under the illusion that he was the best player

(2)

: an instance of such deception

had/harbored no illusions about the difficulty of the task

b

obsolete : the action of deceiving

3

: a fine plain transparent bobbinet or tulle usually made of silk and used for veils, trimmings, and dresses

illusional

i-ˈlü-zh(ə-)nəl 

adjective

Illustration of illusion

• a and b are equal in length

Did you know?

Allusion and Illusion

Allusion and illusion may share some portion of their ancestry (both words come in part from the Latin word ludere, meaning “to play”), and sound quite similar, but they are distinct words with very different meanings. An allusion is an indirect reference, whereas an illusion is something that is unreal or incorrect. Each of the nouns has a related verb form: allude “to refer indirectly to,” and illude (not a very common word), which may mean “to delude or deceive” or “to subject to an illusion.”

Synonyms of illusion

• dream
• fantasy
• vision
• daydream
• delusion
• unreality
• idea

Choose the Right Synonym for illusion

delusion, illusion, hallucination, mirage mean something that is believed to be true or real but that is actually false or unreal.

delusion implies an inability to distinguish between what is real and what only seems to be real, often as the result of a disordered state of mind.

delusions of persecution

illusion implies a false ascribing of reality based on what one sees or imagines.

an illusion of safety

hallucination implies impressions that are the product of disordered senses, as because of mental illness or drugs.

suffered from terrifying hallucinations

mirage in its extended sense applies to an illusory vision, dream, hope, or aim.

claimed a balanced budget is a mirage

Examples of illusion in a Sentence

The video game is designed to give the illusion that you are in control of an airplane.

They used paint to create the illusion of metal.

She says that all progress is just an illusion.

Recent Examples on the Web

The Hering and Wundt illusions are examples of how straight lines can appear curved if intersecting lines cross them at a certain angle. — Emma Gometz, Scientific American, 22 Sep. 2026

In the flickering flame of firelight, the stutters take on a zoetrope effect, creating the illusion of rhinos in motion. — Literary Hub, 22 Sep. 2026

Twenty-five hundred years ago, the Greek philosopher Zeno set about making the case for the counterintuitive claim that all motion is an illusion. — Kathryn Schulz, New Yorker, 21 Sep. 2026

Unfortunately for many, the illusion of Lane Kiffin can get the best of you. — Trey Wallace Outkick, FOXNews.com, 20 Sep. 2026

Word History

Etymology

Middle English illusioun "mockery, derision, deception, something that deceives the senses or imagination," borrowed from Anglo-French & Late Latin; Anglo-French illusion, borrowed from Late Latin illūsiōn-, illūsiō, going back to Latin, "ridicule," from illūdere "to make fun of, speak mockingly of, fool, dupe" (from il- il- + lūdere "to play, jest, amuse oneself, trifle with, tease") + -tiōn-, -tiō, suffix of verbal action — more at ludicrous

First Known Use

14th century, in the meaning defined at sense 2b

Phrases Containing illusion

• optical illusion

Rhymes for illusion

• allusion
• collusion
• conclusion
• confusion
• contusion
• delusion
• diffusion
• effusion
• exclusion
• extrusion
• inclusion
• infusion

Kids Definition

illusion

noun

il·​lu·​sion il-ˈü-zhən 

1

: a misleading image presented to the eye

2

: the state or fact of being led to accept as true something unreal or imagined

3

: a mistaken idea

Medical Definition

illusion

noun

il·​lu·​sion il-ˈü-zhən 

1

: a misleading image presented as a visual stimulus

2

a

: perception of something objectively existing in such a way as to cause misinterpretation of its actual nature

especially : optical illusion compare delusion sense 2

b

: hallucination sense 1

c

: a pattern capable of reversible perspective

illusional

-ˈüzh-nəl, -ən-ᵊl 

adjective