Wiktionary
n. (context poker English) The losing of a hand after being the mathematical favorite to win at the start of the hand.
Wikipedia
In poker, bad beat is a subjective term for a hand in which a player with what appear to be strong cards nevertheless loses. It most often occurs where one player bets the clearly stronger hand and their opponent makes a poor call that eventually "sucks out" and wins. There is no consensus among poker players as to what exactly constitutes a bad beat and often players will disagree about whether a particular hand was a bad beat. A few examples are: quads over full house, quads over quads, straight flush over quads, small full house vs. bigger full house or better.
Bad Beat is a 2012 American short drama film, written and directed by Nicholas Conde and produced by the Kings Gambit. The film appeared in competition at the 2012 Campus Moviefest at the University of South Florida where it was rewarded Best Drama before proceeding to the national competition in Hollywood.
Usage examples of "bad beat".
The voice of the woman who had sat all night in a cafe on Columbus Street listening to bad beat-generation verse and rattling her glass and stomping her feet with the best of them as the rest of her withered and curled up like an old rose and died inside.