unfun vs unsound

unfun

adj

  • Not fun. 

noun

  • Lack or absence of fun; funlessness. 

unsound

adj

  • Not good, unreliable. 

  • Not whole, not solid, defective. 

  • Infirm, diseased. 

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