unreasonable
Americanadjective
-
not reasonable or rational; acting at variance with or contrary to reason; not guided by reason or sound judgment; irrational.
an unreasonable person.
-
not in accordance with practical realities, as attitude or behavior; inappropriate.
His Bohemianism was an unreasonable way of life for one so rich.
- Synonyms:
- nonsensical, stupid, absurd, preposterous, silly, foolish, senseless
-
excessive, immoderate, or exorbitant; unconscionable.
an unreasonable price; unreasonable demands.
- Synonyms:
- extravagant
-
not having the faculty of reason.
adjective
-
immoderate; excessive
unreasonable demands
-
refusing to listen to reason
-
lacking reason or judgment
Other Word Forms
Etymology
Origin of unreasonable
First recorded in 1300–50, unreasonable is from the Middle English word unresonabel. See un- 1, reasonable
Explanation
To be unreasonable means acting in an irrational way. Your expectation that your favorite team will win the Super Bowl every year is unreasonable. When someone's unreasonable, they're not using reason, or common sense, to make decisions or demands. Add the prefix un- to reasonable, "having sound judgment," and you get an adjective that's perfect for describing illogical behavior. It's often used for a certain kind of demanding stubbornness too: "It's completely unreasonable to make your server take your soup back five times to warm it up a little more."
Vocabulary lists containing unreasonable
"The Southpaw"
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Chronically Dolores
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Part 3 Vocabulary (Unit 2)
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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.
She made the video montage of my mom for her memorial, which was extra difficult because a family member had all sorts of unreasonable demands.
From Los Angeles Times ● Aug. 6, 2026
An employee who believes a request is unreasonable or inconsistently applied should first raise the issue with a manager or HR and explain how the rule is affecting their comfort or ability to work safely.
From BBC ● Aug. 5, 2026
They acknowledge some uncertainties over traffic impact, but don’t think Transurban is unreasonable to suggest that the changes are neutral for valuation.
From The Wall Street Journal ● Aug. 4, 2026
"The United States is using its lawful authority to obtain the elimination of unreasonable acts, policies, and practices that burden US commerce," said Kush Desai, a White House spokesperson, in a statement.
From Barron's ● Aug. 3, 2026
It was not unreasonable for him to anticipate his own death— he had been ill for so long, and the doctors could not figure out what was wrong with him.
From "Charles and Emma: The Darwins' Leap of Faith" by Deborah Heiligman
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.
