Article 366 contains definitions of key terms used in the Constitution, such as 'Anglo-Indian', 'Article', 'Borrow', 'Clause', 'Federal Court', 'Goods and Services Tax', etc.

Article 366: Interpretation clause defining 31 terms used in Constitution: Anglo-Indian, Article, Borrow, Clause, Federal Court, Goods and Services Tax, Goods and Services Tax Council, India, Existing law, etc. Ensures uniform interpretation of constitutional provisions. Definitions can be amended by Parliament via ordinary law (not constitutional amendment) unless context otherwise requires.