Internal, a.
Etymology: [L. internus; akin to interior. See Interior.]
1. Inward; interior; being within any limit or surface; inclosed; -- opposed to external; as, the internal parts of a body, or of the earth.
2. Derived from, or dependent on, the thing itself; inherent; as, the internal evidence of the divine origin of the Scriptures.
3. Pertaining to its own affairs or interests; especially, (said of a country) domestic, as opposed to foreign; as, internal trade; internal troubles or war.
4. Pertaining to the inner being or the heart; spiritual. With our Savior, internal purity is everything. Paley.
4 more senses
5. Intrinsic; inherent; real. [R.] The internal rectitude of our actions in the sight of God. Rogers.
6. (Anat.)
Lying toward the mesial plane; mesial. Internal angle (Geom.), an interior angle. See under Interior. -- Internal gear (Mach.), a gear in which the teeth project inward from the rim instead of outward.
Syn. -- Inner; interior; inward; inland; inside.
Shades of meaning
Fernald has no entry of its own for internal; he lists it under inherent.
He lists it without comment; the entries above explain its neighbors.