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
Derived 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 to contact the Social Security Administration proactively is not unreasonable.
From MarketWatch • Jun. 5, 2026
Tilbury inserted herself into the deal negotiations as discussions progressed and made financial demands that became increasingly complex and unreasonable, the people said.
From The Wall Street Journal • May 22, 2026
"At the moment, with the exams, they're under an awful lot of pressure. So I don't think it's unreasonable for them to go and have a cup of coffee as a group and work together."
From BBC • May 15, 2026
Because in a world in which there’s some constraint on political gerrymandering, it’s not unreasonable for folks to think, Well, let’s really put some teeth into that constraint in our state.
From Slate • May 7, 2026
“Belinda,” remonstrated Mr. Pocket, from the other end of the table, “how can you be so unreasonable? Jane only interfered for the protection of baby.”
From "Great Expectations" by Charles Dickens
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.
