cavil vs tergiversate

cavil

verb
  • To criticise for petty or frivolous reasons. 

noun
  • A petty or trivial objection or criticism. 

tergiversate

verb
  • To change sides or affiliation; to apostatize. 

  • To evade, to equivocate using subterfuge; to obfuscate in a deliberate manner. 

  • To flee by turning one's back. 

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