interior (adj.) Look up interior at Dictionary.com
late 15c., from Middle French intérieur and directly from Latin interior "inner, interior, middle," comparative adjective of inter "within" (see inter-). Meaning "of the interior parts of a country" is from 1777; meaning "internal affairs of a country or state" (as in U.S. Department of the Interior) is from 1838. Interior decoration first attested 1807. Interior design from 1927.
interior (n.) Look up interior at Dictionary.com
"part of a country distant from the coast," 1796, from interior (adj.); meaning "inside of a building or room" is from 1829.