deny vs impugn

deny

verb
  • To disclaim connection with, responsibility for, etc.; to refuse to acknowledge; to disown; to abjure; to disavow. 

  • To assert that something is not true. 

  • To refuse to give or grant something to someone. 

  • To disallow or reject. 

  • To take something away from someone; to deprive of. 

  • To prevent from scoring. 

impugn

verb
  • To verbally assault, especially to argue against an opinion, motive, or action; to question the truth or validity of. 

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