Source : Webster's Revised Unabridged Dictionary (1913)

Kernel \Ker"nel\, n. [OE. kernel, kirnel, curnel, AS. cyrnel,
   fr. corn grain. See {Corn}, and cf. {Kern} to harden.]
   1. The essential part of a seed; all that is within the seed
      walls; the edible substance contained in the shell of a
      nut; hence, anything included in a shell, husk, or
      integument; as, the kernel of a nut. See Illust. of
      {Endocarp}.

            ' A were as good crack a fusty nut with no kernel
                                                  --Shak.

   2. A single seed or grain; as, a kernel of corn.

   3. A small mass around which other matter is concreted; a
      nucleus; a concretion or hard lump in the flesh.

   4. The central, substantial or essential part of anything;
      the gist; the core; as, the kernel of an argument.

Kernel \Ker"nel\, v. i. [imp. & p. p. {Kerneled}or {Kernelled};
   p. pr. & vb. n. {Kerneling} or {Kernelling}.]
   To harden or ripen into kernels; to produce kernels.

Source : WordNet®

kernel
     n 1: the inner and usually edible part of a seed or grain or nut
          or fruit stone; "black walnut kernels are difficult to
          get out of the shell" [syn: {meat}]
     2: a single whole grain of a cereal; "a kernel of corn"
     3: the choicest or most essential or most vital part of some
        idea or experience; "the gist of the prosecutor's
        argument"; "the heart and soul of the Republican Party";
        "the nub of the story" [syn: {substance}, {core}, {center},
         {essence}, {gist}, {heart}, {heart and soul}, {inwardness},
         {marrow}, {meat}, {nub}, {pith}, {sum}, {nitty-gritty}]
     [also: {kernelling}, {kernelled}]

Source : Free On-Line Dictionary of Computing

kernel
     
        (Note: NOT "kernal").
     
        1.  The essential part of {Unix} or other
        {operating system}s, responsible for resource allocation,
        low-level hardware interfaces, security etc.  See also
        {microkernel}.
     
        2.  An essential subset of a programming language,
        in terms of which other constructs are (or could be) defined.
        Also known as a {core} language.
     
        (1996-06-07)