Interior

n.
  1. That which is within; the internal or inner part of a thing; the inside.
  2. The inland part of a country, state, or kingdom.
    3. Department of the Interior ,
    that department of the government of the United States which has charge of pensions, patents, public lands and surveys, the Indians, education, etc.; that department of the government of a country which is specially charged with the internal affairs of that country; the home department.
    Secretary of the Interior ,
    the cabinet officer who, in the United States, is at the head of the Department of the Interior.