disquisitive vs investigational

disquisitive

adj
  • Relating to disquisition; fond of discussion or investigation; inquisitive. 

investigational

adj
  • Of, or relating to investigating, or to an investigation. 

  • of, or relating to an unapproved drug or chemical entity being studied. 

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