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.
He also described a previous proposal of increasing business rates on large warehouses to help reduce them for pubs and clubs as "delusional".
From BBC ● Aug. 27, 2026
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
A few months ago, that would have sounded like the delusional ramblings of someone with no chance at winning.
From Los Angeles Times ● Aug. 20, 2026
Because when I think about it, I was also built from delusional optimism and folly.
From "Please Ignore Vera Dietz" by A.S. King
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.
