In poker terms, a bad beat is a good hand that got beat by an even better hand. Needless to say, good hands lose all the time, but generally a bad beat would be a full house losing to a better [full house], or a [four of a kind], etc.

Here's an example for [Texas Hold 'em]. I hold [pocket rockets], the [flop] shows ace, ten, nine. I bet strong because I just made a three of a kind. My opponent calls. [Fourth street] shows another ten. I bet again, I have aces full of tens now, an excellent hand. Here comes [the river], a three. No help to me, but I bet again because of the strength of my hand. My opponent calls. He shows a pair of tens in the hole and he made a four of a kind using the community cards, and wins. Now that is a bad beat.

Quite a few card clubs also have progressive bad beat jackpots. In order to win the [jackpot] in the club I've been to, you have to have aces full of tens or better and get beat. The other stipulation is that you have to use both your [hole cards], assuming the game is Texas Hold 'em. The nice thing about these jackpots is that the person who got the bad beat takes 50% of the jackpot, the winner takes 25%, and everyone else who played that hand at the table splits the remaining 25%, also known as the [table share]. I think that is a pretty common breakdown of the winnings at most clubs as well.

bad beat (idea)