delusional
Americanadjective
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having false or unrealistic beliefs or opinions.
Senators who think they will get agreement on a comprehensive tax bill are delusional.
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Psychiatry. maintaining fixed false beliefs even when confronted with facts, usually as a result of mental illness.
He was so delusional and paranoid that he thought everybody was conspiring against him.
Etymology
Origin of delusional
First recorded in 1850–60; delusion ( def. ) + -al 1 ( def. )
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Which is not to say Yee is delusional.
From Los Angeles Times • Mar. 8, 2026
Numerous studies have found that in its eagerness to agree with the user, the model validated unhealthy or dangerous behaviour, and even led people to delusional thinking.
From BBC • Feb. 13, 2026
By August, as problems with users suffering from delusional psychosis appeared in media reports, OpenAI attempted to retire 4o entirely and replace it with a new version, named GPT-5.
From The Wall Street Journal • Feb. 10, 2026
While the “number of users” once meant “number of paying users,” the success of Facebook, Instagram and other social-media sites persuaded delusional investors that the word “paying” could be dropped.
From MarketWatch • Feb. 6, 2026
As his behavior became more and more irrational, more and more delusional, the last of his friends were driven away.
From "Into the Wild" by Jon Krakauer
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
