Kernel [kûr’nəl] is a noun that refers to the edible substance that you find inside nuts, or to a grain or seed enclosed in a husk. The term can also be used more broadly to identify the central or core part of any structure. That is why the central part of most computer operating systems is also called a kernel.
In my grandfather’s day, rushing corn from field to pot was the only way to get the optimum sweetness, because once it was picked, its kernels would begin to convert their sugar to starch. (NY Times)
The security companies are also upset that Microsoft has taken steps in certain versions of Vista to prevent any software from penetrating what is called the kernel — the core of the operating system. (NY Times)