belibel vs denigrate

belibel

verb
  • To libel or traduce; to calumniate. 

denigrate

verb
  • To criticise so as to besmirch; traduce, disparage or defame. 

  • To treat as worthless; belittle, degrade or disparage. 

  • To blacken. 

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