hebetate vs vacuous

hebetate

adj
  • obtuse; dull 

  • Having a dull or blunt and soft point 

verb
  • To render obtuse; to dull; to blunt. 

vacuous

adj
  • Empty; void; lacking meaningful content. 

  • Showing a lack of thought or intelligence; vacant. 

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