1. a group of states, organizations, or regions that have joined together to form a larger political or administrative unit while maintaining some independence
2. the act or process of forming such a union

Examples

• The Russian Federation consists of many different republics and regions.
• The American Federation of Labor was formed to protect workers’ rights.
• The federation of European nations created new opportunities for trade.
• Each state in the federation maintains its own local government.
• The sports federation oversees competitions across multiple countries.
• The federation was established through a series of treaties and agreements.