hebetate vs mellow out

hebetate

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

adj
  • obtuse; dull 

  • Having a dull or blunt and soft point 

mellow out

verb
  • To become mellow, or to change from uptight to relaxed. 

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