delusion

noun de·lu·sion \ di-ˈlü-zhən , dē- \

|Updated on: 15 Jul 2018

Definition of delusion

1 a : something that is falsely or delusively believed or propagated

under the delusion that they will finish on schedule

delusions of grandeur

b psychology : a persistent false psychotic belief regarding the self or persons or objects outside the self that is maintained despite indisputable evidence to the contrary

the delusion that someone was out to hurt him

; also : the abnormal state marked by such beliefs

2 : the act of tricking or deceiving someone : the state of being deluded

… accused the Bohemian of having practised the most abominable arts of delusion among the younger brethren.
—Walter Scott

—

delusional

play \-ˈlüzh-nəl, -ˈlü-zhə-nᵊl\ adjective

—

delusionary

play \-zhə-ˌner-ē\ adjective

See delusion defined for English-language learners

See delusion defined for kids

Examples of delusion in a Sentence

He has delusions about how much money he can make at that job.
He is living under the delusion that he is incapable of making mistakes.
She is under the delusion that we will finish on time.
As the illness progressed, his delusions took over and he had violent outbursts.

Recent Examples of delusion from the Web

The structural forces behind the Republicans’ Russia delusion make that a forbidding examination.

— The Economist, "The Trump-Putin summit in Helsinki," 5 July 2018
The collective delusion is underlined by a moment in the film when Alec Baldwin, Donald Trump’s most prominent comic interpreter, says there’s no way the man will become president.

— akiva gottlieb, latimes.com, "A new documentary about 'The King' finds links between Elvis Presley and the decline of the American Dream," 29 June 2018
As the juggernaut of Brexit rolls into view, British politicians seem to be operating under the same delusion.

— georgina voss, The Atlantic, "Brexit Could Cripple Britain’s Ports," 20 June 2018
Dunn has been diagnosed with schizoaffective disorder, a mental health condition characterized by hallucinations and delusions.

— keith bierygolick, Cincinnati.com, "Why did Ohio man hold woman captive in Blanchester shed? An imaginary prostitution ring.," 14 June 2018
Those who recognized the self-delusion and incompetence began referring to the Green Zone as the Emerald City.

— evan osnos, The New Yorker, "Trump vs. the “Deep State”," 14 May 2018
The ensuing years haven't been exactly kind to that delusion, but hey.

— aimee levitt, Chicago Reader, "Archive Dive / Gender Issues / Music How the Reader reviewed Exile in Guyville when it first came out," 7 May 2018
Butler was diagnosed with schizoaffective disorder, characterized by hallucinations, delusions, impulse control and manic behavior, according to the National Alliance on Mental Illness.

— anita chabria and darrell smith, sacbee, "This mother is demanding a test for DNA, even if it proves her son is guilty of rape | The Sacramento Bee," 4 May 2018
But given Milk's elevated opinion of herself, and quick descent into delusion this episode, who knows?

— joey guerra, Houston Chronicle, "'RuPaul's Drag Race All Stars 3' recap: Spilled Milk," 8 Feb. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'delusion.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of delusion

Middle English, from Late Latin delusion-, delusio, from deludere — see delude

NEW! Time Traveler

First Known Use: 15th century

in the meaning defined at sense 2

See Words from the same year

delusion Synonyms

Synonym Discussion of delusion

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

Other Psychology Terms

fetish, hypochondria, intelligence, mania, narcissism, neurosis, pathological, psychosis, schadenfreude, subliminal

DELUSION Defined for English Language Learners

delusion

noun

Definition of delusion for English Language Learners

: a belief that is not true : a false idea
: a false idea or belief that is caused by mental illness

DELUSION Defined for Kids

delusion

noun de·lu·sion \ di-ˈlü-zhən \

Definition of delusion for Students

: a false belief that continues in spite of the facts

“You might be laboring under the delusion that the entire … world is impressed with you …”
—J. K. Rowling, Goblet of Fire

Medical Dictionary

delusion

noun de·lu·sion \ di-ˈlü-zhən \

medical Definition of delusion

1 a : the act of deluding : the state of being deluded

b : an abnormal mental state characterized by the occurrence of psychotic delusions

2 : a false belief regarding the self or persons or objects outside the self that persists despite the facts and occurs in some psychotic states — compare hallucination 1, illusion 2a