Kernel

1. (n.) 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.
2. (n.) A single seed or grain; as, a kernel of corn.
3. (n.) A small mass around which other matter is concreted; a nucleus; a concretion or hard lump in the flesh.
4. (n.) The central, substantial or essential part of anything; the gist; the core; as, the kernel of an argument.
5. (v. i.) To harden or ripen into kernels; to produce kernels.