The Collaborative International Dictionary of English v.0.48:

Internal \In*tern"al\, a. [L. internus; akin to interior. See
   Interior.]
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   1. Inward; interior; being within any limit or surface;
      inclosed; -- opposed to external; as, the internal parts
      of a body, or of the earth.
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   2. Derived from, or dependent on, the thing itself; inherent;
      as, the internal evidence of the divine origin of the
      Scriptures.
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   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.
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   4. Pertaining to the inner being or the heart; spiritual.
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            With our Savior, internal purity is everything.
                                                  --Paley.
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   5. Intrinsic; inherent; real. [R.]
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            The internal rectitude of our actions in the sight
            of God.                               --Rogers.
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   6. (Anat.) Lying toward the mesial plane; mesial.
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   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.
        [1913 Webster] Internal-combustion