Latin had an elegant grammatical trick: it could turn prepositions into comparative adjectives. The preposition inter (between) became interior (more inward), just as extra became exterior, super became superior, and infra became inferior. This pattern reveals something about how Romans conceptualised space — not as fixed positions but as degrees of relative depth, height, and distance. The word 'interior' entered English in the late 15th century, initially as an adjective for anything inner or inland. Its use as a noun — the interior of a house, a car, a country — developed over the following two centuries. The political sense emerged in the 18th century: a 'Ministry of the Interior' handles domestic affairs, governing what lies within the nation's borders rather than its foreign relations. Perhaps the most surprising descendant of this root is 'intimate,' from Latin intimus, the superlative form meaning 'innermost.' An intimate friend is literally the most inward person in your life, the one who reaches the deepest interior of your confidence and trust.