(1):

(n.) The inland part of a country, state, or kingdom.

(2):

(n.) That which is within; the internal or inner part of a thing; the inside.

(3):

(a.) Remote from the limits, frontier, or shore; inland; as, the interior parts of a region or country.

(4):

(a.) Being within any limits, inclosure, or substance; inside; internal; inner; - opposed to exterior, or superficial; as, the interior apartments of a house; the interior surface of a hollow ball.