The Collaborative International Dictionary of English v.0.48:

Core \Core\, n. [OF. cor, coer, cuer, F. c[oe]ur, fr. L. cor
   heart. See Heart.]
   1. The heart or inner part of a thing, as of a column, wall,
      rope, of a boil, etc.; especially, the central part of
      fruit, containing the kernels or seeds; as, the core of an
      apple or quince.
      [1913 Webster]

            A fever at the core,
            Fatal to him who bears, to all who ever bore.
                                                  --Byron.
      [1913 Webster]

   2. The center or inner part, as of an open space; as, the
      core of a square. [Obs.] --Sir W. Raleigh.
      [1913 Webster]

   3. The most important part of a thing; the essence; as, the
      core of a subject; -- also used attributively, as the core
      curriculum at a college.
      [1913 Webster +PJC]

   4. (Founding) The portion of a mold which shapes the interior
      of a cylinder, tube, or other hollow casting, or which
      makes a hole in or through a casting; a part of the mold,
      made separate from and inserted in it, for shaping some
      part of the casting, the form of which is not determined
      by that of the pattern.
      [1913 Webster]

   5. A disorder of sheep occasioned by worms in the liver.
      [Prov. Eng.] --Halliwell.
      [1913 Webster]

   6. (Anat.) The bony process which forms the central axis of
      the horns in many animals.
      [1913 Webster]

   7. (Elec.) A mass of iron or other ferrous metal, forming the
      central part of an electromagnet, such as those upon which
      the conductor of an armature, a transformer, or an
      induction coil is wound.

   Note: The presence of the iron intensifies the magnetic field
         created by a a current passing through the windings.
         [Webster 1913 Suppl. +PJC]

   8. (mining) a sample of earth or rock extracted from
      underground by a drilling device in such a manner that the
      layers of rock are preserved in the same order as they
      exist underground; as, to drill a core; to extract a core.
      The sample is typically removed with a rotating drill bit
      having a hollow center, and is thus shaped like a
      cylinder.
      [PJC]

   9. (Computers) The main working memory of a digital computer
      system, which typically retains the program code being
      executed as well as the data structures that are
      manipulated by the program. Contrasted to ROM and data
      storage device.

   Note: The term was applied originally to the main memory,
         consisting of small ferromagnetic rings, that were used
         to store data in older computers, where each ring
         representing one bit of information by virtue of its
         state of magnetization. They were superseded by
         electronic data storage devices.

   Syn: core memory, random access memory, RAM
        [PJC]

   10. (Geol.) the central part of the earth, believed to be a
       sphere with a radius of about 2100 miles, and composed
       primarily of molten iron with some nickel. It is
       distinguished from the crust and mantle.
       [PJC]

   11. (Engineering) the central part of a nuclear reactor,
       containing the fissionable fuel.
       [PJC]

   Core box (Founding), a box or mold, usually divisible, in
      which cores are molded.

   Core print (Founding), a projecting piece on a pattern
      which forms, in the mold, an impression for holding in
      place or steadying a core.

   Core dump See core dump in the vocabulary.
      [1913 Webster]