equivocate vs prevaricate

equivocate

verb
  • To render equivocal or ambiguous. 

  • To speak using double meaning; to speak ambiguously, unclearly or doubtfully, with intent to deceive. 

prevaricate

verb
  • To shift or turn from direct speech or behaviour; to deviate from the truth; to evade the truth; to waffle or be (intentionally) ambiguous. 

  • To undertake something falsely and deceitfully, with the purpose of defeating or destroying it. 

  • To collude, as where an informer colludes with the defendant, and makes a sham prosecution. 

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