资料来源 : Webster's Revised Unabridged Dictionary (1913)

   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.