unsound

This word describes a failure of integrity, whether that integrity is logical, physical, or mental. It suggests a hidden or systemic weakness that makes something unreliable or dangerous. In intellectual contexts, it refers to a gap in logic. Unlike "wrong," which might just be a factual error, "unsound" implies the entire foundation of the argument is broken. When applied to structures, it carries a sense of imminent risk or decay. It is more clinical and serious than "shaky" or "wobbly," often used in official safety reports or engineering audits. In legal or medical contexts regarding the mind, it is a formal designation. It indicates a lack of capacity rather than a specific personality trait or temporary mood.