1. A small group of indispensable persons or things Noun
2. The center of an object Noun
3. The central part of the Earth Noun
4. The choicest or most essential or most vital part of some idea or experience Noun
5. A cylindrical sample of soil or rock obtained with a hollow drill Noun
6. An organization founded by James Leonard Farmer in 1942 to work for racial equality Noun
7. The central meaning or theme of a speech or literary work Noun
8. (computer science) a tiny ferrite toroid formerly used in a random access memory to store one bit of data; now superseded by semiconductor memories Noun
9. The chamber of a nuclear reactor containing the fissile material where the reaction takes place Noun
10. A bar of magnetic material (as soft iron) that passes through a coil and serves to increase the inductance of the coil Noun