Ultimate failure is when something does not end the way you wanted it to. It means something did not go as planned and you did not reach the goal that you were trying to reach. It can mean a lot of different things depending on the situation - it could mean not doing as well as you wanted on a test, or not winning a game, or not getting a job you applied for, or not being able to buy what you wanted. In any case, it means you didn't reach the goal that you wanted to reach.