What Puts the "S" in Super?

Many films center around the central theme of super heroes. Whether decorated with a dazzling cape or in everday clothes, I got to thinking as I indulged my inner child by watching the loveable cartoon movie "Megamind", what makes a superhero super? Is it in who they are or how they act? As a writing prompt for fellow writers out there, what do you feel makes a superhero super? Feel free to post your thoughts/answers.