core

KOR/kɔɹ/UKKAW/kɔː/

Noun pluralcores

29 meanings of core

1
most importantadjective
Being the most important part of something.
Like the main beam of a house that holds everything up.
Reading is a core skill for every student.
Honesty is one of their core values.
UsageOften before a noun: core values. Or say core to something.
Similarcentral, key, fundamental, essential, basic
Oppositeperipheral, secondary, marginal, minor
2
central ideanouncountable or uncountable
The most important part of an idea or thing.
Like the main point of a story, the part you must not lose.
Honesty is at the core of their friendship.
The core of the problem was a lack of money.
UsageSay at the core of something.
Similaressence, heart, crux, nub, kernel
Note
3
processor (chip)nouncountable or uncountable
One of several processors built into a single computer chip.
Like having many workers on one team, each doing a job at once.
Each core handles a separate task at the same time.
A faster core improves how quickly programs run.
UsageOften dual-core or quad-core.
Note
4
nouncountable or uncountable
The middle or innermost part of a thing or place.
Like the middle of a pizza, away from the edges.
The core of the city is full of tall buildings.
Few people live in the desert's core.
Oppositeperiphery, edge, outskirts, fringe
Note
5
stomach musclesnouncountable or uncountable
The set of muscles around your stomach and lower back.
Like a tree trunk that keeps the whole body steady.
Planks help build a strong core.
Yoga strengthened her core over several months.
UsageSay your core or the core.
Similarmidsection
Note
6
nouncountable or uncountable
A long round sample of rock, ice or body tissue taken out for testing.
Like pushing a straw into a cake and pulling out a round piece.
Geologists studied the core for signs of oil.
The drill brought up a long rock core from deep underground.
Similarsample
7
nuclear reactornouncountable or uncountable
The middle part of a nuclear reactor where the reaction happens.
Like the engine of a car, where the real power is made.
Engineers must keep the reactor core cool at all times.
If the core overheats, it can melt.
Note

Less common meanings

8
fruit centernouncountable or uncountable
The middle part of a fruit that holds its seeds.
Like the middle of an apple where the seeds hide.
She threw the apple core into the compost bin.
Cut around the core before slicing the pear.
UsagePeople often say apple core.
Note
9
remove seedsverbtransitive
To take out the middle part of a fruit where the seeds are.
Like scooping out the middle so only the soft fruit is left.
Core the apples before you bake them.
She cored the pear and sliced it thin.
10
nounneologismcountable
A style or look popular online, built around one theme, with names like cottagecore.
Like a fashion trend that gets its own name, such as cottagecore.
Every few months, a new core like cottagecore takes over the internet.
Cottagecore was the first core she fell in love with.
Similaraesthetic, style
Note
11
verbtransitive
To drill a round hole through something, often to take out a sample.
Like pushing a stick straight through the middle of an apple.
Workers had to core the wall to run the new pipe.
The machine cored the block of stone in seconds.
Similardrill, bore
12
iron (magnet)nouncountable or uncountable
A piece of iron inside a coil that makes the magnet stronger.
Like a path that guides water, it guides the magnetic pull.
Winding wire around an iron core makes a stronger magnet.
The core inside the coil boosts the magnetic field.
13
cardboard tubenouncountable or uncountable
The hollow cardboard tube in the middle of a roll of paper or tape.
Like the cardboard tube left after a roll of paper towels is used up.
When the paper towels ran out, only the cardboard core was left.
She saved every paper towel core for her kids' art projects.
Similartube
Note
14
noun
The center of an atom, its nucleus and inner electrons but not the outer ones.
15
noun
The middle layer between the two outer surfaces of a layered material like a sandwich panel.
16
noun
The middle part of a nuclear bomb that holds the material that explodes.
17
adjective
Deeply and truly part of a sport's culture, not just a casual fan.
18
nouncolloquial
Ellipsis of core memory. An older, casual name for a computer's main working memory.
19
noun
When things are sorted into groups, the members that people most easily see as belonging to a group.
20
noun
The inside part of a folded protein, made mostly of parts that push water away.
21
noun
The part of a mold that makes a hollow space or hole inside the finished piece.
22
noun
The bony inside part that forms the center of an animal's horn.
23
noun
The biggest and most varied main group within a larger family of related living things.
24
noun
The set of deals that no group of people could do better on by going off on their own.
25
noun
Money you pay extra for a rebuilt part, given back when you return the old part.
26
noundialectal
The set time a miner spends working underground, called a shift.
27
nounobsolete
A sheep illness caused by worms living in the liver.
[the skin of the sheep] is clear from cores and jogs under the jaws.
1750, William Ellis, Modern Husbandry or Practice of Farming
28
nounobsolete
A group of people.
He was in a core of people.
1622, Francis, Lord Verulam
29
noun
An old Hebrew and Phoenician unit for measuring amounts of grain or liquid.

Practice

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Origins

Meanings 1–9, 11–13

From Middle English core, meaning the core or pith of an apple. Its origin is unclear.

Checked 31 Oct 2026 · 2 facts

Core comes from Middle English core, meaning apple-core or pith. en.wiktionary.org
Its earlier origin is unclear. en.wiktionary.org

Meaning 10

From the suffix -core, which comes from Etymology 1.

Checked 31 Oct 2026 · 2 facts

This sense of core derives from the suffix -core. en.wiktionary.org
The suffix ultimately derives from core under Etymology 1. en.wiktionary.org