Unsound: meaning, definitions and examples

Typically used to describe decisions, arguments, or structures that are not based on solid reasoning or are structurally weak. It does not usually refer directly to mental health.

• His business plan was unsound and led to significant losses.
• The bridge was closed because it was considered structurally unsound.

Carries a strong negative connotation and is used to describe someone whose mental state is severely disturbed, often to the point of being dangerous or irrational.

• The deranged man was shouting nonsense in the street.
• She looked at him with a deranged glint in her eyes.

Can be used to describe someone who is emotionally or mentally inconsistent and unreliable. It carries a moderate negative connotation and can also be used for physical descriptions.

• His emotionally unstable behavior made it difficult to maintain a relationship.
• The weather has been quite unstable lately, shifting from sunshine to storms in minutes.

A clinical term used to describe someone diagnosed with a mental disorder. It is a neutral term and is often used in medical or formal contexts.

• He has been diagnosed as mentally ill and is receiving treatment.
• People who are mentally ill should have access to proper healthcare.

Similar to the first description – again, not based on solid reasoning or secure condition. Usually indicates something is dubious or risky.

• The investment opportunity was unsound; it had too many risks.
• The health of the building was unsound after the earthquake.

Commonly used in contexts where something is not legally or logically acceptable, such as arguments, tickets, or data.

• Your argument is invalid due to the lack of evidence.
• The password you entered is invalid.

Applied to something that has defects or imperfections, often used for products, plans, or theories.

• The vase is beautiful but flawed with a tiny crack.
• Her plan was clever but deeply flawed in execution.

Refers to someone or something that cannot be depended upon, often describing people, machines, or sources of information.

• He is an unreliable worker; he often misses deadlines.
• The weather forecast is notoriously unreliable.