From The Collaborative International Dictionary of English v.0.48:
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.
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'A were as good crack a fusty nut with no kernel
--Shak.
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2. A single seed or grain; as, a kernel of corn.
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3. A small mass around which other matter is concreted; a
nucleus; a concretion or hard lump in the flesh.
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4. The central, substantial or essential part of anything;
the gist; the core; as, the kernel of an argument.
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From The Collaborative International Dictionary of English v.0.48:
Kernel \Ker"nel\, v. i. [imp. & p. p. Kerneledor Kernelled;
p. pr. & vb. n. Kerneling or Kernelling.]
To harden or ripen into kernels; to produce kernels. Kerneled