fed ‧ e ‧ ra ‧ tion AC /ˌfedəˈreɪʃ ə n/ BrE AmE noun
1 . [countable] a group of organizations, clubs, or people that have joined together to form a single group ⇨ confederation :
the National Federation of Women’s Institutes
2 . [countable] a group of states that have joined together to form a single group:
the Russian Federation
3 . [uncountable] when groups of people, states etc join together to form a larger group