Confederation - (noun)
(1) A trade union confederation is an organisation that brings together affiliated trade unions to further the interests of trade unions at national and international levels. (2) An organisation that comprises various groups that work together to achieve common business or political goals.
Source: (1) Own Definition (2) Cambridge Dictionary
Example of Use: (1) The European Trade Union Confederation comprises 90 national trade union confederations and 10 European trade union federations. (2) Employers also come together to lobby governments. The Portuguese employers’ confederation, for example, represents 79 sectoral and regional associations.