core
n//ko(ː)ɹ//kärnhus, kärna
The central part of a fruit, containing the kernels or seeds.
The most important part of a thing or aggregate of things wherever located and whether of any determinate location at all; the essence.
(printing) A hollow cylindrical piece of cardboard around which a web of paper or plastic is wound.
(engineering, manufacturing) The portion of a mold that creates a cavity or impression within the part (casting or molded part) or that makes a hole in or through the part.