Kernel
KERNEL (O.E. cyrnel, a diminutive of " corn," seed, grain), the soft and frequently edible part contained within the hard outer husk of a nut or the stone of a fruit; also used in botany of the nucleus of a seed, the body within its several integuments or coats, and generally of the nucleus or core of any structure; hence, figuratively, the pith or gist of any matter.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)
