certainty vs surety

certainty

noun
  • The state of being certain. 

  • A fact or truth unquestionably established. 

  • An instance of being certain. 

surety

noun
  • Certainty. 

  • A promise to pay a sum of money in the event that another person fails to fulfill an obligation. 

  • One who undertakes to pay money or perform other acts in the event that his principal fails therein. 

  • A substitute; a hostage. 

  • Evidence; confirmation; warrant. 

  • That which makes sure; that which confirms; ground of confidence or security. 

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