core

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The central or innermost part.
• noun The hard or fibrous central part of certain fruits, such as the apple or pear, containing the seeds.
• noun The basic or most important part; the crucial element or essence: synonym: substance.
• noun A set of subjects or courses that make up a required portion of a curriculum.
• noun Electricity A soft iron rod in a coil or transformer that provides a path for and intensifies the magnetic field produced by the windings.
• noun Computers A memory, especially one consisting of a series of tiny doughnut-shaped masses of magnetic material.
• noun One of the magnetic doughnut-shaped masses that make up such a memory.
• noun Geology The central portion of the earth below the mantle, beginning at a depth of about 2,900 kilometers (1,800 miles) and probably consisting of iron and nickel. It is made up of a liquid outer core and a solid inner core.
• noun A mass of dry sand placed within a mold to provide openings or shape to a casting.
• noun A reactor core.
• noun A cylindrical sample of rock, ice, or other material obtained from the center of a mass by drilling or cutting.
• noun The base or innermost part, such as soft or inferior wood, surrounded by an outer part or covering, such as veneer wood.
• noun Archaeology A stone from which one or more flakes have been removed, serving as a source for such flakes or as a tool itself.
• noun Anatomy The muscles in the trunk of the human body, including those of the abdomen and chest, that stabilize the spine, pelvis, and shoulders.
• transitive verb To remove the core or innermost part from.
• transitive verb To remove (a cylindrical sample) from something, such as a glacier.
• transitive verb To remove a cylindrical sample from (a glacier or soil layer, for example).
• transitive verb To remove small plugs of sod from (turf) in order to aerate it.
• transitive verb To form or build with a base or innermost part consisting of a different substance from that of the covering or outer part.
• adjective Of basic importance; essential.
• adjective Anatomy Of or relating to the muscles of the trunk of the human body.

from The Century Dictionary.

• noun In mining, the number of hours, generally from six to eight, during which each party of miners works before being relieved. The miner's day is thus usually divided into three or four cores or shifts.
• noun A body.
• noun A body of persons; a party; a crew; a corps.
• noun Chosen; directed.
• To make, mold, or cast on a core.
• To remove the core of, as of an apple or other fruit.
• To roll in salt and prepare for drying: applied to herrings.
• noun The heart or innermost part of anything; hence, the nucleus or central or most essential part, literally or figuratively: as, the core of a question.
• noun Specifically— The central part of a fleshy fruit, containing the seeds or kernels: as, the core of an apple or a quince.
• noun In architecture, the inner part or filling of a wall or column.
• noun In medicine, the fibrous innermost part of a boil.
• noun In molding, the internal mold of a casting, which fills the space intended to be left hollow.
• noun In telegraphy, the central cord of insulated conducting wires in a submarine or subterranean cable.
• noun The iron nucleus of an electromagnet.
• noun In rope-making, a central strand around which other strands are twisted, as in a wire rope; or a cable.
• noun In hydraulic engineering, an impervious wall or structure, as of concrete, in an embankment or dike of porous material, to prevent the passage of water by percolation.
• noun The cylindrical piece of rock obtained in boring by means of the diamond drill or any other boring-machine which makes an annular cut. Also called carrot.
• noun The bony central part of the horn of a ruminant; a horn-core, or process of the frontal bone.
• noun In prehistoric archæol., a piece of flint, obsidian, or similar material, from which knives and other stone implements have been chipped.
• noun The center or innermost part of any open space.
• noun A disorder in sheep caused by worms in the liver.
• noun An internal induration in the udder of a cow.

from the GNU version of the Collaborative International Dictionary of English.

• noun A Hebrew dry measure; a cor or homer.
• noun obsolete A body of individuals; an assemblage.
• noun (Mining.) A miner's underground working time or shift.
• transitive verb To take out the core or inward parts of.
• transitive verb To form by means of a core, as a hole in a casting.