[dih-loo-zhuh n] /dɪˈlu ʒən/
an act or instance of deluding.
the state of being deluded.
a false belief or opinion:
"delusions of grandeur."
Psychiatry. a fixed false belief that is resistant to reason or confrontation with actual fact:
"a paranoid delusion."
1375–1425; late Middle English < Latin dēlūsiōn- (stem of dēlūsiō), equivalent to dēlūs(us) (past participle of dēlūdere; see delude) + -iōn- -ion
Related forms
delusional, delusionary, adjective
predelusion, noun
Can be confused
allusion, delusion, elusion, hallucination, illusion (see synonym study at illusion)
1. deception. See illusion.
Example Sentences for delusions
Eve, come away, and let us not believe these vain delusions.
Let those people keep their crazy delusions if it's what's keeping them happy.
Tomlinson's delusions were harmless, and not widely shared.
The author comes at her characters from every angle, laying bare their compromises and delusions.
Their delusions of grandeur do not extend as far as seeing thing that aren't there.
He was skeptical of the morals of industrialists and newspaper publishers but receptive to the delusions of quacks.
As the delusions get deeper, so does the gross stuff.
Other unusual behavior that could result from use includes confusion, delusions and hallucinations.
And it is said that psychotic breaks-with their delusions and, in some cases, hallucinations-can be brought on by great stress.
He hears voices, and he suffers from hallucinations and delusions.
British Dictionary definitions for delusions
delusion (dɪˈluːʒən)
1.  a mistaken or misleading opinion, idea, belief, etc: he has delusions of grandeur
2.  psychiatry illusion See also hallucination a belief held in the face of evidence to the contrary, that is resistant to all reason
3.  the act of deluding or state of being deluded

Collins English Dictionary - Complete & Unabridged 10th Edition
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Word Origin and History for delusions
"act of misleading someone," early 15c.; as a form of mental derangement, 1550s. See delude. Technically, delusion is a belief that, though false, has been surrendered to and accepted by the whole mind as a truth; illusion is an impression that, though false, is entertained provisionally on the recommendation of the senses or the imagination, but awaits full acceptance and may not influence action. Delusions of grandeur, the exact phrase, is recorded from 1840, though the two words were in close association for some time before that.
Online Etymology Dictionary, © 2010 Douglas Harper
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delusions in Medicine

delusion de·lu·sion (dĭ-lōō'zhən)
A false belief strongly held in spite of invalidating evidence, especially as a symptom of mental illness.

de·lu'sion·al adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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delusions in Science
A false belief strongly held in spite of invalidating evidence, especially as a symptom of mental illness, as in schizophrenia.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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delusions in Culture

delusion definition

A false belief held despite strong evidence against it; self-deception. Delusions are common in some forms of psychosis. Because of his delusions, the literary character Don Quixote attacks a windmill, thinking it is a giant.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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