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. )
Explanation
A delusional person believes things that couldn't possibly be true. If you're convinced that the microwave is attempting to control your thoughts, you are, sadly, delusional. Delusional comes from a Latin word meaning "deceiving." So delusional thinking is kind of like deceiving yourself by believing outrageous things. Delusional thoughts are often a sign of mental illness, but the word can also be used more loosely to describe behavior that is just not realistic. If your friend thinks he's going to get rich playing video games, he's probably not mentally ill, but it's not a stretch to call him delusional.
Vocabulary lists containing delusional
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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.
They know their cognition will continue to fade, and they might live for years in an agitated, delusional state where they’ll need round-the-clock care from people they don’t recognize.
From MarketWatch ● Jul. 20, 2026
For Slattery, what begins as an exercise in comic self-demolition gradually becomes the movie’s biggest surprise, with the actor turning a desperate, delusional version of himself into its most unexpectedly lovable character.
From Los Angeles Times ● Jul. 6, 2026
"I don't want to come on here and be delusional that there is no process, there is no forces at work which are challenging the prime minister as leader," Kyle added.
From BBC ● Jun. 21, 2026
For the retired—and sometimes delusional and occasionally demented—residents of the Boroughs, mortality is already a preoccupation.
From The Wall Street Journal ● May 21, 2026
To Steve Eisman at FrontPoint Partners, the market seemed mainly stupid or delusional: A financial culture that had experienced so many tiny panics followed by robust booms saw any sell-off as merely another buying opportunity.
From "The Big Short" by Michael Lewis
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.
