The Indian Federation has been called the 'Union of States' in the Indian Constitution. This term is used to describe the federal structure of India, which is a union of states with a central government that has powers over national issues.

Features of the Indian Federation:

1. Federal structure: India has a federal form of government where power is divided between the central government and the state governments. The Constitution defines the powers and responsibilities of each level of government.

2. Supremacy of the Constitution: The Indian Constitution is the supreme law of the land. All laws and actions of the government must be in accordance with the Constitution.

3. Dual polity: The Indian Federation has a dual polity where both the central government and the state governments have their own jurisdictions and powers.

4. Division of powers: The Constitution provides for a division of powers between the centre and the states. The central government has powers over matters of national importance such as defence, foreign policy, and currency while the states have powers over matters related to their territory.

5. Independent judiciary: The Constitution provides for an independent judiciary that acts as a check on the powers of the government.

6. Written Constitution: The Indian Constitution is a written document that outlines the rights and duties of citizens, the structure of government, and the distribution of powers between the centre and the states.

Conclusion:

In conclusion, the Indian Federation is a unique system of government that combines features of both a unitary and federal system. The Constitution defines the powers and responsibilities of each level of government, ensuring a balance of power and autonomy for the states within the larger framework of a united India.