The Supreme Court is best characterized as  a federal court.
Explanation:
In US the federal court is highest court of law in the country and is  viable to take all the decisions that are there from the state courts and can overturn them or make corrections.
There are certain cases where only the federal court can do proceedings too.
This is also the name that is used by other countries for the paramount or the highest court in the country and it is called the Supreme court of the country.
It wields all the same of the above powers and is the one that manages all state courts.