a bar of magnetic material (as soft iron) that passes through a coil and serves to increase the inductance of the coil
the chamber of a nuclear reactor containing the fissile material where the reaction takes place
(computer science) a tiny ferrite toroid formerly used in a random access memory to store one bit of data; now superseded by semiconductor memories; "each core has three wires passing through it, providing the means to select and detect the contents of each bit"
the choicest or most essential or most vital part of some idea or experience; "the gist of the prosecutor's argument"; "the heart and soul of the Republican Party"; "the nub of the story"
the central meaning or theme of a speech or literary work
a small group of indispensable persons or things; "five periodicals make up the core of their publishing program"