doubt vs equivocation

doubt

noun
  • Disbelief or uncertainty (about something); (countable) a particular instance of such disbelief or uncertainty. 

verb
  • To be undecided about; to lack confidence in; to disbelieve, to question. 

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. 

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