To bet means to risk money on a game or event to win more money. People do this in sports or games for fun or profit.
I will bet ten dollars on the game.
She bets every week on horse races.
This meaning refers to a formal or legal agreement to risk money on an event, like in official gambling or betting houses.
He lost his bet at the casino.
The bet was placed according to legal rules.
To bet can also mean you are sure or believe something will happen. You say this to show confidence, not always about money.
I bet it will rain tomorrow.
She bet he would arrive late again.
A bet can mean a sure thing. It is something very likely to happen or be true, like when you trust a result.
This team is a safe bet to win.
Buying a house is a good bet for the future.
In informal speech, people say ‘bet’ to show they agree or confirm something quickly. It is like saying ‘yes’ or ‘sure’.
‘Will you come?’ ‘Bet!’
I bet we will have fun there.
Bet can mean to challenge someone to do something, usually without money. It is like making a fun promise or test.
I bet you can't run fast.
She bet me I would not jump that high.