In "The Lottery," in what sense is the story’s title ironic?

The title is one of situational irony as it develops in the story. The term "lottery" suggests an opportunity to win something of value, a nice prize or perhaps a large amount of money. The odds of winning a lottery are very small because many people usually participate, but for the lucky winner, the pay-off is very nice indeed. In this story, however, the irony lies in the fact that the person who "wins" the lottery loses his or her life in an especially terrible way. As we slowly begin to realize what the lottery is really all about, the horror of the story grows until its final savage conclusion.