unsound
Americanadjective
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not sound; unhealthy, diseased, or disordered, as the body or mind.
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decayed or impaired, as timber or foods; defective.
- Synonyms:
- unwholesome, rotten
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not solid or firm, as foundations.
-
not well-founded or valid; fallacious.
an unsound argument.
-
easily broken; light.
unsound slumber.
-
not financially strong; unreliable.
an unsound corporation.
adjective
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diseased, weak, or unstable
of unsound mind
-
unreliable or fallacious
unsound advice
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lacking solidity, strength, or firmness
unsound foundations
-
of doubtful financial or commercial viability
an unsound enterprise
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(of fruit, timber, etc) not in an edible or usable condition
Other Word Forms
- unsoundly adverb
- unsoundness noun
Etymology
Origin of unsound
Middle English word dating back to 1275–1325; un- 1, sound 2
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’s right about that, but this manual included some unsound science.
From The Wall Street Journal • Feb. 8, 2026
A charter school also can be denied renewal if it is fiscally unsound, but district staff concluded that, too, was not grounds for denial.
From Los Angeles Times • Oct. 16, 2025
The castle may have been demolished because it was structurally unsound or damaged in enemy attacks.
From BBC • Sep. 17, 2025
The judge pointed out that there was no evidence to support that theory, and he faulted the prosecutors for legally unsound charges, like alleging assault while making claims about actions merely being negligent.
From Slate • May 9, 2024
Although swidden does permit the forest to regrow, it is wildly inefficient and environmentally unsound.
From "1491" by Charles C. Mann
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.
