spurious vs unfounded

spurious

adj
  • False, not authentic, not genuine. 

  • Extraneous; stray; not relevant or wanted. 

unfounded

adj
  • Having no strong foundation; not based on solid reasons or facts. 

  • Not having been founded or instituted. 

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