One meaning of lottery is gambling, so the title suggests that the event is risky and that someone one can either win (saving his or her life) or lose (his or her life).
Shirley Jackson also makes use of the title of the story in order to create suspense. At the beginning, as preparations for the lottery are described, it is not clear what kind of event it is. One would suppose it is a way of raising money by selling ticket numbered tickets and giving prizes to those picked at random. However, it is until the first stone is thrown that the reader learns the real nature of the lottery.
