[ uhn-sound ]
See synonyms for unsound on Thesaurus.com
adjective,un·sound·er, un·sound·est.
  1. not sound; unhealthy, diseased, or disordered, as the body or mind.

  2. decayed or impaired, as timber or foods; defective.

  1. not solid or firm, as foundations.

  2. not well-founded or valid; fallacious: an unsound argument.

  3. easily broken; light: unsound slumber.

  4. not financially strong; unreliable: an unsound corporation.

Origin of unsound

Middle English word dating back to 1275–1325; see origin at un-1, sound2

Other words for unsound

Other words from unsound

  • un·sound·ly, adverb
  • un·sound·ness, noun

Words Nearby unsound

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use unsound in a sentence

  • Would they set a precedent and redefine the law because they viewed it as legally unsound?

    How to Try a Nazi | Richard Rashke | September 6, 2013 | THE DAILY BEAST
  • Your religion does not make it—its ethics are too weak, its theories too unsound, its transcendentalism is too thin.

    God and my Neighbour | Robert Blatchford
  • But it was in the course of this period 1834-47 that persons of unsound mind became recognised as a distinct class.

  • Coronado, on his part, hooted in his soul at Mrs. Stanley's whimsies, and half supposed her to be of unsound mind.

    Overland | John William De Forest
  • Bois l'Hery's horses were unsound, Schwalbach's gallery was a swindle, Moessard's articles a recognised blackmail.

    The Nabob | Alphonse Daudet
  • His letters and speeches also show that he was not conversant with political economy, and that his social views were unsound.

British Dictionary definitions for unsound


/ (ʌnˈsaʊnd) /

  1. diseased, weak, or unstable: of unsound mind

  2. unreliable or fallacious: unsound advice

  1. lacking solidity, strength, or firmness: unsound foundations

  2. of doubtful financial or commercial viability: an unsound enterprise

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

Derived forms of unsound

  • unsoundly, adverb
  • unsoundness, noun

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