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.
We are in the seventh year of the Roaring 2020s, an idea I first wrote about in August 2020, when it looked delusional.
From MarketWatch ● Aug. 26, 2026
“I could be delusional, but I don’t think I am, so I will pay for her love.”
From Slate ● Aug. 22, 2026
“You have to be delusional to be in a band,” Armstrong said.
From Los Angeles Times ● Aug. 5, 2026
Psychiatric researchers are referring to the confluence of three characteristics—sycophancy, linguistic alignment and hyperpersonalization—as the “amplification spiral,” suggesting it’s the mechanism by which delusional thinking can fester.
From The Wall Street Journal ● Jun. 28, 2026
They were all laughing, though, so apparently Ridge hadn’t said anything that sounded completely delusional.
From "The First State of Being" by Erin Entrada Kelly
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.
