delusion

noun de·lu·sion \ di-ˈlü-zhən , dē- \

Updated on: 20 May 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

All Cost Less Than $200 travel-and-eats GQ's Best New Restaurants in America, 2018 Little puppet boys like Albert Breer gladly toted the water for the owners and their mass delusion.

— drew magary, GQ, "NFL Owners Are Hopelessly Damaged Human Beings," 26 Apr. 2018
Both serve as mirrors of our own collective delusion.

— t.d. williams, The Root, "How the West Was Lost," 26 Apr. 2018
But authorities in Illinois and Colorado shared past reports suggesting multiple red flags about a disturbed man with paranoid delusions.

— CBS News, "BMW theft solved too late to prevent deadly Waffle House rampage," 24 Apr. 2018
Meanwhile, authorities in Illinois shared past reports suggesting multiple red flags about a disturbed young man with paranoid delusions.

— Washington Post, "Waffle House slaying suspect arrested after massive manhunt," 23 Apr. 2018
Meanwhile, authorities in Illinois shared past reports suggesting multiple red flags about a disturbed young man with paranoid delusions.

— sheila burke, The Seattle Times, "Waffle House slaying suspect arrested after massive manhunt," 23 Apr. 2018
Meanwhile, authorities in Illinois shared past reports suggesting multiple red flags about a disturbed young man with paranoid delusions.

— Bloomberg.com, "Waffle House Slaying Suspect Arrested After Massive Manhunt," 23 Apr. 2018
Fleabag was a dubious narrator, a fabulist with delusions of grandeur and a smart-ass retort for everyone.

— rachel syme, The New Republic, "In Killing Eve, Two Women Are Fed Up and Dangerous," 6 Apr. 2018
The panel determined that the most likely explanation was mass psychogenic illness (MPI), which is essentially a collective delusion among a cohesive group of people that a sickness is spreading among them.

— beth mole, Ars Technica, "Brain-damaging “health attacks” spur US to permanently cut Cuba embassy staff," 5 Mar. 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