To make better, or improve, something perceived to be in a negative condition.
To become better; improve.
To convert (a situation, thing, etc.) into something better.
To carry forward the stake and winnings from a bet on to a subsequent wager or series of wagers.
To increase (an asset, money, etc.) by gambling or investing in a daring manner.
A bet or series of bets where the stake and winnings are cumulatively carried forward; an accumulator.