Inner (adjective)

1. Situated or occurring within the limits of a particular area or space.
2. Relating to the innermost part of something or someone.

Origin:

From middle english inner, iner, from old english in(ne)ra, superlative of in ("in, on") + -ra.

Examples:

1. The inner layer of the earth's atmosphere.
2. The inner workings of a clock.
3. The inner city is known for its high crime rate.
4. She revealed her innermost thoughts and feelings to the therapist.
5. The inner circle of advisors to the president are privy to classified information.