delusion
noun
de·lu·sion
di-ˈlü-zhən 
dē-
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
Walter ScottExamples 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 on the Web
In certain contexts, that unrestrained flattery might lead to psychological distress: In recent months, there have been growing reports of individuals experiencing AI psychosis, in which extensive conversations with chatbots may have amplified delusions.
—Lila Shroff, The Atlantic, 24 July 2025
That's a chronic mental health condition where a person experiences symptoms of schizophrenia, such as hallucinations or delusions, and mood disorders like depression.
—Steve Drummond, NPR, 23 July 2025
Psychologist Sandra Klein, though, said Barahona seemed unable to move past delusions that included missing evidence and pictures that just don’t exist.
—Miami Herald, 23 July 2025
Some of the more alarming results included all the models looked at struggling with delusions, which is where a patient harbors a false belief that persists despite clear evidence to the contrary.
—PC Magazine, 13 July 2025
See All Example Sentences for delusion
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Lila Shroff, The Atlantic, 24 July 2025
That's a chronic mental health condition where a person experiences symptoms of schizophrenia, such as hallucinations or delusions, and mood disorders like depression.
—Steve Drummond, NPR, 23 July 2025
Psychologist Sandra Klein, though, said Barahona seemed unable to move past delusions that included missing evidence and pictures that just don’t exist.
—Miami Herald, 23 July 2025
Some of the more alarming results included all the models looked at struggling with delusions, which is where a patient harbors a false belief that persists despite clear evidence to the contrary.
—PC Magazine, 13 July 2025
See All Example Sentences for delusion
Cite this Entry
“Delusion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/delusion. Accessed 1 Aug. 2025.
Copy CitationKids Definition
delusion
noun
de·lu·sion
di-ˈlü-zhən
1
: the act of deluding : the state of being deluded
2
a
: a mistaken or misleading belief
b
: a false belief that persists despite evidence proving it false and occurs especially in some mentally disturbed states
Medical Definition
delusion
noun
de·lu·sion
di-ˈlü-zhən
1
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 sense 1, illusion sense 2a
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