equivocation vs vagueness

equivocation

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

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

vagueness

noun
  • Something which is vague, or an instance or example of vagueness. 

  • The condition of being unclear; vague. 

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