A federal union refers to a political system that combines several states or regions to form a larger entity. This type of system can have different names depending on the particular country or situation involved. Some of the synonyms for federal union are confederation, federation, coalition, alliance, bloc, and commonwealth. A confederation usually implies a loose union of independent states with a limited central government. In contrast, a federation often has a stronger central government with a defined role over the states. An alliance, bloc, or coalition describes an agreement between multiple parties for specific purposes, while a commonwealth denotes a political entity that shares cultural, historical, or legal ties.