Definition

1. Adjective:
   • Not physically healthy, strong, or whole; damaged, decayed, or diseased: Describes something in poor physical condition.
   • Not based on reliable evidence, reasoning, or facts; flawed or erroneous: Describes an idea, argument, or judgment that is logically defective.
   • Not financially secure or stable; risky or unreliable: Describes a business, investment, or practice that is not economically solid.
   • Suffering from severe mental illness; not mentally competent: Describes a state of mind that is not rational or healthy.

Usage and Examples

• Describing physical condition:
  • The inspector declared the building's foundation to be unsound.
  • He couldn't join the army due to an unsound heart.
• Describing logic or ideas:
  • The theory was rejected because it was built on unsound principles.
  • Her conclusion is unsound; the data does not support it.
• Describing financial status:
  • The bank was shut down for unsound lending practices.
  • Investing in that company would be unsound.
• Describing mental state:
  • The court ruled he was of unsound mind at the time of the crime.

Advanced Usage

• "of unsound mind": A legal and formal phrase meaning not mentally competent to be responsible for one's actions or decisions.
  • The will was contested on grounds that the testator was of unsound mind.
• "unsound sleep": Sleep that is not deep or restful.
  • She had a night of unsound sleep, troubled by worries.

Variants and Related Words

• Unsoundly (adverb): In an unsound manner.
  • The structure was unsoundly built.
• Unsoundness (noun): The state or quality of being unsound.
  • The unsoundness of the bridge caused great concern.

Synonyms

• Faulty: Containing a defect or flaw.
• Defective: Imperfect or not working properly.
• Fallacious: Based on a mistaken belief or unsound reasoning.
• Unreliable: Not able to be trusted or depended on.
• Unstable: Not steady and likely to change or fail.

Antonyms

• Sound: In good condition; based on valid reasoning; financially secure; mentally healthy.
• Solid: Strong and reliable in construction, argument, or finance.
• Valid: Having a sound basis in logic or fact.
• Healthy: In good physical or mental condition.

Related Phrases

• "Found unsound": Determined to be defective or unsafe after examination.
  • The timber was found unsound and replaced.
• "Render unsound": To cause something to become defective or unstable.
  • The flood rendered the building's structure unsound.

Adjective

1. of e.g. advice
2. physically unsound or diseased
   • has a bad back
   • a bad heart
   • bad teeth
   • an unsound limb
   • unsound teeth
3. suffering from severe mental illness
   • of unsound mind
4. containing or based on a fallacy
   • fallacious reasoning
   • an unsound argument
5. not sound financially
   • unsound banking practices
6. not in good condition; damaged or decayed
   • an unsound foundation