Noun:
1: core the center of an object; "the ball has a titanium core"
2: nucleus, core, core group a small group of indispensable persons or things; "five periodicals make up the core of their publishing program"
3: core the central part of the Earth
4: heart, nub, marrow, nitty-gritty, gist, kernel, essence, sum, inwardness, meat, heart and soul, core, center, substance, pith 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"
5: core a cylindrical sample of soil or rock obtained with a hollow drill
6: congress of racial equality, core an organization founded by James Leonard Farmer in 1942 to work for racial equality
7: burden, gist, essence, core, effect the central meaning or theme of a speech or literary work
8: core the chamber of a nuclear reactor containing the fissile material where the reaction takes place
9: core a bar of magnetic material (as soft iron) that passes through a coil and serves to increase the inductance of the coil
Verb:
1: core remove the core or center from; "core an apple"