parlay vs side bet

parlay

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

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. 

side bet

noun
  • A bet on some aspect of a game or competition that is not the main bet of the game or the prize of the competition; proposition bet. 

  • An investment of time, money, or resources that reinforces one's commitment to a course of action. 

  • An investment or risk undertaken by a company that is not part of its core business. 

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