Bettor (noun)

1. A person who makes a bet or wager.
2. A person who engages in gambling.

Origin:

From bet + -or, one who bets or makes a wager.

Examples:

1. The bettor placed a bet on the winning horse.
2. The bettor won a large sum of money.
3. The bettor was a regular at the casino.
4. The bettor's strategy was to bet on the underdog.
5. The bettor's luck finally ran out and he lost all his money.