inward; interior; being within any limit or surface; inclosed; -- opposed to external; as, the internal parts of a body, or of the earth.-derived from, or dependent on, the thing itself; inherent; as, the internal evidence of the divine origin of the scriptures.-pertaining to its own affairs or interests; especially, (said of a country) domestic, as opposed to foreign; as, internal trade; internal troubles or war.-pertaining to the inner being or the heart; spiritual.-intrinsic; inherent; real.-lying toward the mesial plane; mesial.