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

As Nick and Jacki’s conversations deepen, the line between witness and participant blurs, forcing both to confront what justice demands, what belief requires, and the perilous distance between true freedom and the illusion of self-determination. —Greg Evans, Deadline, 9 Feb. 2026

This work by Franco-Isreali artist Yorame Mevorach, also known as Oyoram, gives the illusion of swimming along the river’s edge. —Kasia Dietz, Condé Nast Traveler, 9 Feb. 2026

The 7/8 length falls right at my ankle, though, giving me the illusion of longer legs. —Melony Forcier, InStyle, 8 Feb. 2026

That illusion of understanding is what experts say deserves more scrutiny. —Kurt Knutsson, FOXNews.com, 7 Feb. 2026

Word History

Etymology

Middle English, from Anglo-French, from Late Latin illusion-, illusio, from Latin, action of mocking, from illudere to mock at, from in- + ludere to play, mock — 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