Who Is the Fat Lady and Why Is It Over When She Sings?

It ain’t over till the fat lady sings simply means that you shouldn’t presume to know the outcome of something while it’s still in progress. The phrase is generally understood to be a reference to opera sopranos, who were traditionally overweight. In Wagner’s opera Der Ring des Nibelungen, the “fat lady” is Brunhilda, who is presented as a very buxom lady. Her farewell scene lasts almost 20 minutes and leads directly to the finale. The first recorded use the phrase appeared in the Dallas Morning News on March 10, 1976: 

Despite his obvious allegiance to the Red Raiders, Texas Tech sports information director Ralph Carpenter was the picture of professional objectivity when the Aggies rallied for a 72–72 tie late in the SWC tournament finals. "Hey, Ralph," said Bill Morgan, "this... is going to be a tight one after all." "Right", said Ralph, "the opera ain’t over until the fat lady sings.”