it ain't over till the fat lady sings

The phrase "it ain't over till the fat lady sings" is an idiom that means a situation or event is not yet finished or concluded until the final and decisive moment, often used when there is still a possibility of a comeback or unexpected outcome. It is typically used to express the idea that one should not prematurely assume the final result until everything has been completed or resolved. The phrase originated in the world of opera, where a larger female singer often performs the concluding aria or climactic scene, hence the reference to a "fat lady."