An accumulator is multiple bet which wagers a single stake on four or more selections. All the selections must win their events for the accumulator to generate a return.
The term accumulator bet is sometimes used to describe a bet with four selections, with self-descriptive terms like fivefold, sixfold and sevenfold used to describe multiple bets with more than four selections.
Example:
A punter places a $5 accumulator bet on:
Ireland winning the Six Nations Championship at 7/1
Munster winning the Heineken Cup at 4/1
Leicester winning the Guinness Premiership at 4/1
The Sharks winning the Super 14 at 6/1
If Ireland wins the Six Nations, the $40 payout will be automatically wagered on Munster. A Munster win will generate a $200 payout which will then be wagered on Leicester.
If Leicester goes on to win the Guinness Premiership the $200 payout will automatically be wagered on the Sharks. If the Sharks win the Super 14 the punter will earn a total payout of $1400.
A loss by any of the selections will result in both the stake and winnings being forfeited.