A betslip that contains two or more selections. Compared to a system bet, the bet is only won if all of the individual bets in the betslip are won. The odds for the bet is calculated by multiplying all the individual odds.
Combination bets are often named based on the number of selection made: Double (2), Treble (3), 4-fold, 5-fold, etc.
A player bets €10 on 3 outcomes 1)Liverpool to win against Arsenal, odds 2.30 2) Manchester City to win against Newcastle, odds 1.40 and 3) Tottenham to win against Watford, odds 1.75. The total odds are: 2.30 * 1.40 * 1.75 = 5.635. The potential payout is 5.64 * €10 = €56.35. The player only wins if all of the individual bets is won, if any of the outcomes is settled as a loss the whole bet is lost.