delusion

noun de·lu·sion \ di-ˈlü-zhən , dē- \

|Updated on: 12 Aug 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

Yesterday, Trump tweeted out a letter from Kim lavishing praise on him, as evidence that his delusion is reality.

— andrew sullivan, Daily Intelligencer, "Did Trump Just Help Stop Brexit?," 13 July 2018
Some researchers have questioned the neurological testing by Penn doctors, while others have continued to speculate that malfunctioning surveillance equipment, covert weapons, or collective delusion may be behind the cases.

— beth mole, Ars Technica, "Brain injury, sound-attack fears spread in China as more Americans evacuated," 2 July 2018
Defense Attorney James Hartke says Elliott got in the hole without being pushed, had her cell phone with her and went along with Dunn's delusions.

— keith bierygolick, Cincinnati.com, "Why did Ohio man hold woman captive in Blanchester shed? An imaginary prostitution ring.," 14 June 2018
The president’s delusions enabled him to lionize himself at the expense of logic and reason, the author says.

— lucy diavolo, Teen Vogue, "Top Takeaways From Michael Wolff’s “Fire And Fury”," 9 Jan. 2018
Despite the fact that Teri suffered from brain damage and schizophrenia that sometimes resulted in delusions, authorities decided to classify the case as an accident based largely on her statement.

— jsonline.com, "CHAPTER 5: THE GIRL IN THE CAFÉ," 27 Sep. 2017
Aldrin’s lawsuit filed earlier this month in a Florida state court, came a week after children Andrew and Janice filed a petition claiming Aldrin suffers from memory loss, delusions, paranoia and confusion.

— Washington Post, "Buzz Aldrin’s ex-manager says she’s been unfairly defamed," 26 June 2018
Aldrin's lawsuit filed earlier this month in a Florida state court came a week after his children, Andrew and Janice, filed a petition claiming their father was suffering from memory loss, delusions, paranoia and confusion.

— CBS News, "Buzz Aldrin sues two of his children, alleging misuse of his finances and slander," 26 June 2018
And the problem that's always been with this story is that while the separation issue is real, the idea that half the country is demonic and bigoted is a delusion.

— Fox News, "Trump signs order halting separation of families at border," 21 June 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