noun The core, center, or essence of an object or system.
the kernel of an argument
noun The central (usually edible) part of a nut, especially once the hard shell has been removed.
noun A single seed of grain, especially of corn or wheat.
noun The stone of certain fruits, such as peaches or plums.
noun A small mass around which other matter is concreted; a nucleus; a concretion or hard lump in the flesh.
noun The central part of many computer operating systems which manages the system's resources and the communication between hardware and software components.
The Linux kernel is open-source.
noun The core engine of any complex software system.
noun The simplified input to an algorithm that has undergone kernelization.