Other forms: cores, coring
The core is the hard middle of an apple or a pear — the part with the pips that you leave on the plate. Bite round it, throw it into the hedge: that is the core.
From fruit it spreads to everywhere the middle matters: the Earth's core, the core of a nuclear reactor, a core sample drilled out of rock or ice. It also means the essential part, the core of the argument or the core of the problem, and as an adjective it marks what cannot be cut — core values, core subjects, a core team. There is a verb: you core an apple before you bake it. Your core is the ring of muscles round your middle, which is what gyms are selling with a core workout. Rotten to the core means bad the whole way through, not just on the surface.
1nouncoreThe hard central part of a fruit, holding the seeds.
“She cut the apple into quarters and took out the core.”
Patternan apple / pear core · eat / cut around the core · remove the core · an apple corer
2nouncentralThe central part of something other than a fruit — of the earth, of a problem, of a team.
“Temperatures at the Earth's core run to thousands of degrees.”
3nounheartThe most important part of something.
“At the core of the dispute is a simple question about money.”
4adjectiveessentialCentral and essential; not to be dropped.
“Reading is a core subject in every school.”
5verbremoveTo remove the core from a fruit.
“Peel and core the pears before you poach them.”
Too few real examples of this word to estimate which sense is commonest.
core is a central part.
CORE → the centre, as in the CORE of the earth
The core of the earth is its hot centre; the core of an apple is its hard centre, the part with the seeds that is left in your hand.
Core is a genuine puzzle. Middle English had core and coor for the pith of an apple, and nobody has traced it further with any confidence: it may be a native English word standing near corn, meaning seed, or a borrowing of Old French cuer, heart, from Latin cor. The heart version is the neatest story, which is exactly why it deserves suspicion.
Middle English
core
English, today
core
Built from
From Middle English core. From Middle English core, kore, coor (“apple-core, pith”), of unknown origin. Possibly of native English origin, from Old English cor, related to Old English coruc, corc (> Middle English cork, crok (“core of an apple or other fruit, heart of an onion”)) and Old English corn (“seed", also "grain”); or alternatively perhaps from Old French cuer (“heart”), from Latin cor (“heart”); or from Old French cors (“body”), from Latin corpus (“body”). Compare also Middle English colk, coke, coll (“the heart or centre of an apple or onion, core”), Dutch kern (“core”), German Kern (“core”). See also heart, corpse. Compare typologically серде́чник, сердцеви́на) (akin to се́рдце, cognate with heart, cor).
Etymology from Wiktionary, CC BY-SA