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Synonyms

unsound

American  
[uhn-sound] / ʌnˈsaʊnd /

adjective

unsounder, unsoundest
  1. not sound; unhealthy, diseased, or disordered, as the body or mind.

    Synonyms:
    unhealthy, ill, sick, infirm
  2. decayed or impaired, as timber or foods; defective.

    Synonyms:
    unwholesome, rotten
  3. not solid or firm, as foundations.

  4. not well-founded or valid; fallacious.

    an unsound argument.

    Synonyms:
    faulty, erroneous, false
  5. easily broken; light.

    unsound slumber.

  6. not financially strong; unreliable.

    an unsound corporation.


unsound British  
/ ʌnˈsaʊnd /

adjective

  1. diseased, weak, or unstable

    of unsound mind

  2. unreliable or fallacious

    unsound advice

  3. lacking solidity, strength, or firmness

    unsound foundations

  4. of doubtful financial or commercial viability

    an unsound enterprise

  5. (of fruit, timber, etc) not in an edible or usable condition

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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

He has said the city government has "grave concerns" about any deployment of troops, labelling the president's approach as "uncoordinated, uncalled for, and unsound".

From BBC • Aug. 24, 2025

Then, following the 1971 Sylmar earthquake, the Wadsworth Hospital building was judged seismically unsound and demolished.

From Los Angeles Times • Aug. 5, 2024

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

It worked in their second game, when the little man overreached himself with an unsound assault.

From "A Dance with Dragons" by George R. R. Martin