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