A more thorough explanation:

A confederacy is a group of states or countries that have come together for mutual support or joint action. It can also refer to an association of two or more people, usually for unlawful purposes.

Examples of a confederacy include:

• The Confederate States of America, which was formed by 11 southern states that seceded from the United States in 1861.
• The European Union, which is a political and economic confederacy of 27 member states.
• A group of criminals who plan to commit a robbery together.

These examples illustrate the definition of a confederacy because they all involve a group of entities coming together for a common purpose. In the case of the Confederate States of America and the European Union, the purpose was to form a political alliance. In the case of the group of criminals, the purpose was to commit a crime together.