unreliable, not safe or in poor condition of a person not competent, unreliable, not capable of forming reliable or acceptable views or thoughts The defendant, a former mental patient, was found to have been of unsound mind at the time of the commission of the crime.
- The defendant presented an unsound argument.
- The judge determined the party was of unsound mind.
- She was alleged to have used unsound accounting methods.
- Unsound is the opposite of sound.