bet 
(bĕt)
(bĕt)n.
1. An agreement usually between two parties that the one who has made an incorrect prediction about an uncertain outcome will forfeit something stipulated to the other; a wager: made a bet that it would stop raining before 2:00.
2. An amount or object risked in a wager; a stake: a bet of $50.
3. One on which a stake is or can be placed: Our team is a sure bet to win.
4.
a. A plan or an option considered with regard to its probable consequence: Your best bet is to make reservations ahead of time.
b. Informal A view or opinion, especially about something that cannot be known at the present time: My bet is that the rain will hold off. My bet is he didn't do it.
v. bet or bet·ted, bet·ting, bets
v.tr.
1. To stake (an amount, for example) in a bet.
2. To make a bet with: I bet them that we would be first.
3. To make a bet on (a contestant or an outcome).
4. To maintain confidently, as if making a bet: I bet they were surprised by the news.
v.intr.
Idiom: To make or place a bet.
you bet Informal
Of course; surely.
[Origin unknown.]