1.  The heart or inner part of a thing, as of a column, wall, rope, of a boil, etc.; especially, the central part of fruit, containing the kernels or seeds; as, the core of an apple or quince. [1913 Webster]
"A fever at the core,
Fatal to him who bears, to all who ever bore." [1913 Webster]

2.  The center or inner part, as of an open space; as, the core of a square. Sir W. Raleigh. [1913 Webster]

3.  The most important part of a thing; the essence; as, the core of a subject; -- also used attributively, as the core curriculum at a college. [1913 Webster]

4.  The portion of a mold which shapes the interior of a cylinder, tube, or other hollow casting, or which makes a hole in or through a casting; a part of the mold, made separate from and inserted in it, for shaping some part of the casting, the form of which is not determined by that of the pattern. [1913 Webster]

5.  A disorder of sheep occasioned by worms in the liver. Halliwell. [1913 Webster]

6.  The bony process which forms the central axis of the horns in many animals. [1913 Webster]

7.  A mass of iron or other ferrous metal, forming the central part of an electromagnet, such as those upon which the conductor of an armature, a transformer, or an induction coil is wound.
"The presence of the iron intensifies the magnetic field created by a a current passing through the windings." [Webster 1913 Suppl.]

8.  a sample of earth or rock extracted from underground by a drilling device in such a manner that the layers of rock are preserved in the same order as they exist underground; as, to drill a core; to extract a core. The sample is typically removed with a rotating drill bit having a hollow center, and is thus shaped like a cylinder. [PJC]

9.  The main working memory of a digital computer system, which typically retains the program code being executed as well as the data structures that are manipulated by the program. Contrasted to ROM and data storage device.
"The term was applied originally to the main memory, consisting of small ferromagnetic rings, that were used to store data in older computers, where each ring representing one bit of information by virtue of its state of magnetization. They were superseded by electronic data storage devices." [PJC]

10.  the central part of the earth, believed to be a sphere with a radius of about 2100 miles, and composed primarily of molten iron with some nickel. It is distinguished from the crust and mantle. [PJC]

11.  the central part of a nuclear reactor, containing the fissionable fuel. [PJC]

1.  To take out the core or inward parts of; as, to core an apple. [1913 Webster]
"He's like a corn upon my great toe . . . he must be cored out." [1913 Webster]

2.  To form by means of a core, as a hole in a casting. [1913 Webster]

3.  To extract a cylindrical sample from, with a boring device. See core{8}. [PJC]

core, abbr. US Congress of Racial Equality.

core, n. & v.
--n.
1 the horny central part of various fruits, containing the seeds.
2 a the central or most important part of anything (also attrib. : core curriculum). b the central part, of different character from the surroundings.
3 the central region of the earth.
4 the central part of a nuclear reactor, containing the fissile material.
5 a magnetic structural unit in a computer, storing one bit of data (see BIT(4)).
6 the inner strand of an electric cable, rope, etc.
7 a piece of soft iron forming the centre of an electromagnet or an induction coil.
8 an internal mould filling a space to be left hollow in a casting.
9 the central part cut out (esp. of rock etc. in boring).
10 Archaeol. a piece of flint from which flakes or blades have been removed.
--v.tr. remove the core from.

Idiom:
core memory Computing the memory of a computer consisting of many cores. core time (in a flexitime system) the central part of the working day, when all employees must be present.

Derivative:
corer n.

Etymology:
ME: orig. unkn.

N  intrinsicality, inbeing, inherence, inhesion, subjectiveness, ego, egohood, essence, noumenon, essentialness, essential part, quintessence, incarnation, quiddity, gist, pith, marrow, core, sap, lifeblood, backbone, heart, soul, important part, principle, nature, constitution, character, type, quality, crasis, diathesis, habit, temper, temperament, spirit, humor, grain, disposition, endowment, capacity, capability, moods, declensions, features, aspects, peculiarities, idiosyncrasy, oddity, idiocrasy, diagnostics, derived from within, subjective, intrinsic, intrinsical, fundamental, normal, implanted, inherent, essential, natural, innate, inborn, inbred, ingrained, inwrought, coeval with birth, genetous, haematobious, syngenic, radical, incarnate, thoroughbred, hereditary, inherited, immanent, congenital, congenite, connate, running in the blood, ingenerate, ingenite, indigenous, in the grain, bred in the bone, instinctive, inward, internal, to the manner born, virtual, characteristic, invariable, incurable, incorrigible, ineradicable, fixed, intrinsically, at bottom, in the main, in effect, practically, virtually, substantially, au fond, fairly, character is higher than intellect, come give us a taste of your quality, magnos homines virtute metimur non fortuna, non numero haec judicantur sed pondere, vital spark of heavenly flame.

N  importance, consequence, moment, prominence, consideration, mark, materialness, import, significance, concern, emphasis, interest, greatness, superiority, notability, weight, value, usefulness, gravity, seriousness, solemnity, no joke, no laughing matter, pressure, urgency, stress, matter of life and death, memorabilia, notabilia, great doings, red-letter day, great thing, great point, main chance, the be all and the end all, cardinal point, substance, gist, sum and substance, gravamen, head and front, important part, principal part, prominent part, essential part, half the battle, sine qua non, breath of one's nostrils, cream, salt, core, kernel, heart, nucleus, keynote, keystone, corner stone, trump card, salient points, top sawyer, first fiddle, prima donna, chief, triton among the minnows, 'it', important, of importance, momentous, material, to the point, not to be overlooked, not to be despised, not to be sneezed at, egregious, weighty, of note, notable, prominent, salient, signal, memorable, remarkable, unforgettable, worthy of remark, worthy of notice, never to be forgotten, stirring, eventful, grave, serious, earnest, noble, grand, solemn, impressive, commanding, imposing, urgent, pressing, critical, instant, paramount, essential, vital, all-absorbing, radical, cardinal, chief, main, prime, primary, principal, leading, capital, foremost, overruling, of vital importance in the front rank, first-rate, superior, considerable, marked, rare, significant, telling, trenchant, emphatic, pregnant, tanti, materially, in the main, above all, kat' exochin, par excellence, to crown all, to beat all, expende Hannibalem!.

N  centrality, centricalness, center, middle, focus, core, kernel, nucleus, nucleolus, heart, pole axis, bull's eye, nave, navel, umbilicus, backbone, marrow, pith, vertebra, vertebral column, hotbed, concentration, centralization, symmetry, center of gravity, center of pressure, center of percussion, center of oscillation, center of buoyancy, metacenter, central, centrical, middle, azygous, axial, focal, umbilical, concentric, middlemost, rachidian, spinal, vertebral, middle, midst, centrally.

core bit, core dump, core group, core loss, core out, hard core, magnetic core