Interior (noun)

1. The inside or internal part of something.
2. The inside or internal part of a building, room, vehicle, or container.
3. The inner or domestic part of a country as distinguished from its coastal or frontier regions.

Origin:

From latin interior meaning "inner, internal".

Examples:

1. The interior of the car was in poor condition.
2. The interior designer transformed the room into a luxurious space.
3. He explored the interior of the cave.
4. The interior of the country is mostly covered by forests.
5. She was responsible for the design of the building's interior.