Best definition of federalism?

Federalism is the political principle whereby political entities divide power between a centralized government or the "federal government" and some smaller entities such as "states" in the American system. This system seeks to create a central government capable of ruling a nation, while also allowing for regions to rule their own affairs in areas not designated to the central government.

The definition of Federalism is it is a system of government where there is one strong, central controlling authority or the principles of a political party called the Federalists. An example is one strong government for the entire united states and has a lot of power and where individual states do not have much power.