equivocation vs prevarication

equivocation

noun
  • The use of expressions susceptible of a double signification, possibly intentionally and with the aim of misleading. 

  • A logical fallacy resulting from the use of multiple meanings of a single expression. 

prevarication

noun
  • A false or deceitful seeming to undertake a thing for the purpose of defeating or destroying it. 

  • Evasion of the truth. 

  • A secret abuse in the exercise of a public office. 

  • The collusion of an informer with the defendant, for the purpose of making a sham prosecution. 

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