erroneous vs unsound

erroneous

adj
  • Containing an error; inaccurate. 

  • Derived from an error. 

  • Mistaken. 

  • Deviating from the requirements of the law, but without a lack of legal authority, thus not illegal. 

unsound

adj
  • Not good, unreliable. 

  • Not whole, not solid, defective. 

  • Infirm, diseased. 

How often have the words erroneous and unsound occurred in a corpus of books? (source: Google Ngram Viewer )