harmless vs unsound

harmless

adj
  • Incapable of causing harm or danger; safe. 

  • Not intended to harm; inoffensive. 

unsound

adj
  • Not good, unreliable. 

  • Not whole, not solid, defective. 

  • Infirm, diseased. 

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