pledge vs surety

pledge

noun
  • An asset or person temporarily handed over to guarantee the fulfilment of something promised, under threat of permanent loss of the thing handed over; surety, security, hostage. 

  • A solemn promise to do something. 

  • The personal property so pledged, to be kept until the debt is paid. 

  • A bailment of personal property to secure payment of a debt without transfer of title. 

  • A person who has taken a pledge of allegiance to a college fraternity, but is not yet formally approved. 

  • A drinking toast. 

  • A promise to abstain from drinking alcohol. 

verb
  • To deposit something as a security; to pawn. 

  • To make a solemn promise (to do something). 

  • To give assurance of friendship by the act of drinking; to drink to one's health. 

surety

noun
  • 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. 

  • Certainty. 

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

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