parlay vs pledge

parlay

verb
  • To carry forward the stake and winnings from a bet on to a subsequent wager or series of wagers. 

  • To convert (a situation, thing, etc.) into something better. 

  • To increase (an asset, money, etc.) by gambling or investing in a daring manner. 

noun
  • A bet or series of bets where the stake and winnings are cumulatively carried forward; an accumulator. 

pledge

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. 

noun
  • 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. 

  • 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 promise to abstain from drinking alcohol. 

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