A federation is a group of societies or other organizations which have joined together, usually because they share a common interest.
双语例句
例： the American Federation of Government Employees.
美国政府雇员联合会。
例： the British Athletic Federation.
英国田径联合会。
例： The organization emerged from a federation of six national agencies.
该组织由六家全国性机构的联合组织发展而来。