Synonyms for Core:

adj.

central (adjective)
interior, innermost, middle, central, main, median, nuclear, halfway, midmost, pivotal, midway, focal.
focal (adjective)
central, convergent, essential, asymptotic, key, nuclear, focal.
inward (adjective)
inner, interior, intestinal, visceral, intrinsic, subjective, inward, central, internal, heart, inland.
middle (adjective)
equidistant, half, centralized, mediocre, median, middle, medial, nuclear, midmost, intermediate, mezzo, mean, medium, pivotal, central, half-and-half, middle-of-the-road, halfway, geocentric, mid, axial, middling, Bisecting, average.

n.

alumnus, associate, confederate, commissioner, academician, arriviste, charter member, branch, baby. corona, crater, magnitude, sunspot, Gravamen, stuff, be, quintessence. elemental, fundamental, inherent, basic, raw, rudimentary, natural. leading, predominant, primary, elementary, principal, supreme, prime. beat, blanch, carve, butter, bake, chill, butchery, butcher, blend. the middle, cross-section, center of gravity. dextrose, flesh, peel, pectin, bruising, peelings, nectar, juice, hull. center, gist (noun)
burden, nub, midpoint, meat, middle, pith, quick, midst, essence, kernel, basis, pivot, focus, heart, crux, substance, nucleus, root.
centrality (noun)
focus, middle, nucleus, centrality.
core (noun)
congress of racial equality, essence, center, effect, nucleus, heart, inwardness, gist, marrow, meat, pith, kernel, burden, heart and soul, core group, nitty-gritty, nub, sum, substance.
focus (noun)
crux, magnet, polestar, funnel, gathering, kernel, asymptote, hub, axle, rally, lure, forum, epitome, heart, focus, bottleneck, essence, spirit, meat, nucleus, crossing, center, marrow, plenum, rendezvous, lodestar, soul, intersection.
group (noun)
nucleus, core group.
middle (noun)
bisection, epicenter, pivot, nub, axis, halfway point, midst, midpoint, mediocrity.
nerve center (noun)
epicenter.
nuclear power (noun)
cold fusion, fusion, heavy water, meltdown, fast-breeder reactor, critical mass, atomic energy, nuclear energy.

Other synonyms:

baby, arriviste, confederate, branch, alumnus, dextrose, fundamental, peelings, Gravamen, academician, sunspot, pectin, charter member, basis, inherent, center of gravity. corona, cross-section, elementary, quintessence, stuff, priority, associate, magnitude. nectar. peel, root, hull, flesh, crater, bruising. juice, concern. raw, natural, basic. quick, bottom. nuclear power
cold fusion, fusion, heavy water, meltdown, fast-breeder reactor, critical mass, atomic energy, nuclear energy.

Usage examples for core

  1. Why should the core or thick stem of cabbage be used as food? – School and Home Cooking by Carlotta C. Greer
  2. We are left with a feeling that the matter has been handled but not dealt with: that the knife has not reached the core – Woman and Labour by Olive Schreiner