equivocate vs vacillate

equivocate

verb
  • To render equivocal or ambiguous. 

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

vacillate

verb
  • To swing indecisively from one course of action or opinion to another. 

  • To sway unsteadily from one side to the other; oscillate. 

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