unsound in WordNet English dictionary

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