The word kernel can mean more than one thing.
- The kernel of a seed is all that is within the outer coat of the seed, as the edible substance contained in the shell of a nut; hence, anything included in a shell, husk, or integument. The term kernel can also mean a single seed or grain, as "a kernel of corn".
- The kernel of an operating system is its essential component, such as the Linux kernel.
- In mathematics, kernel has several different, somewhat unrelated meanings; see Kernel (mathematics), or go directly to Kernel (function), Kernel (algebra), or Kernel (category theory).