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.
Your instinct that you’ll never be in a meaningfully lower tax bracket isn’t an unreasonable one, given your good fortune.
From MarketWatch ● Jul. 20, 2026
The judge told the court that Donaldson also left the scene and that he felt the police were not unreasonable saying they feared bail could not be adequately managed.
From BBC ● Jul. 17, 2026
They do this by employing the tried-and-true tactics of the insurance industry of unjustifiable bureaucratic decisions, superpowered by artificial intelligence: prior authorizations, unnecessary delays, claim denials, unreasonable reimbursements.
From The Wall Street Journal ● Jul. 17, 2026
It’s blended with an almost unreasonable amount of lemon zest and juice before coating every ridge of cavatappi.
From Salon ● Jul. 8, 2026
In fact, I am astonished that you would make such an unreasonable request.
From "The Incorrigible Children of Ashton Place: Book I: The Mysterious Howling" by Maryrose Wood
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.
