Webster's Revised Unabridged Dictionary · 1913

parlay

parlay , transitive verb

This is the characteristic act in a common betting system used by gamblers to try to achieve a large win from a small initial stake. Statistically, it is similar to betting a small stake on a game with a large payoff and a proportionately small chance of winning.

1.
To wager the winnings plus the initial stake of one bet on a subsequent wager, or to engage in a series of such increased wagers.
2.
To exploit success in one endeavor so as to achieve greater success in subsequent endeavors.
3.
Figuratively, to transform a gain into something of greater value.

parlay , noun

This is the characteristic act in a common betting system used by gamblers to try to achieve a large win from a small initial stake. Statistically, it is similar to betting a small stake on a game with a large payoff, but with a proportionately small chance of winning.

The act of betting the winnings from a prior bet, plus the original stake, on a subsequent bet; the second or later such bet in a series; also, a series of such bets, with the stakes for later bets coming from the winnings of earlier bets.