English Reference
noun · adjective · verb

core

n. · adj. · v.
US /ˈkɔɹ/ UK /kˈɔː/ core UK spelling cores

  1. 01 B1 Intermediate Botany

    n.the hard central part of a fruit, such as an apple or pear, that contains the seeds.

    n.the central portion of certain fleshy fruits, such as apples or pears, containing the seeds and typically having a tough or fibrous texture.

    Simple

    She ate the whole apple except for the core.

    In context

    After peeling the fruit, the chef used a specialized tool to remove the core without bruising the surrounding flesh.

  2. 02 B2 Upper Intermediate

    n.the most important or central part of a system, organization, or idea.

    n.the foundational or most essential part of an aggregate, system, or abstract concept; the essence.

    Simple

    The core of the problem is that we don't have enough money.

    In context

    At the core of his philosophical argument lies the belief that individual liberty must always outweigh collective security.

  3. 03 B2 Upper Intermediate Science

    n.the central part of a planet or star, which is often very hot or solid.

    n.the innermost layer of a celestial body, such as the Earth's molten outer core and solid inner core.

    Simple

    Scientists study the Earth's core to understand the planet's magnetic field.

    In context

    The fusion reactions occurring within the star's core generate the immense pressure required to prevent gravitational collapse.

  4. 04 C1 Advanced Technical Computing

    n.one of the independent processing units in a computer's CPU.

    n.an independent processing unit within a central processing unit (CPU) that can execute program instructions.

    Simple

    This new laptop has a processor with eight cores for faster performance.

    In context

    The software is optimized for multi-core architectures, allowing it to distribute heavy workloads across several processing units simultaneously.

  5. 05 B2 Upper Intermediate Academic

    adj.describing the most important or basic parts of something.

    adj.constituting the essential, foundational, or most significant part of a whole.

    Simple

    Math and English are core subjects that every student must take.

    In context

    The company decided to sell its secondary businesses to focus on its core competencies and long-term stability.

    Usage

    Usually placed before the noun.

  6. 06 C1 Advanced Technical

    v.to take the center part out of a fruit.

    v.to remove the central part or seeds from a fruit; to extract a cylindrical sample from a larger mass.

    Simple

    You should peel and core the pears before boiling them in the syrup.

    In context

    The geologists spent the afternoon coring the glacier to obtain ice samples for climate analysis.

    Usage

    Transitive verb requiring a direct object.

    hollow outextract

Usage core part · central core · core element

If you cut through the Sun's layers, deep inside is the core where the temperature is 15 million Celsius.

BBC News· 14 Aug 2026

But as the weather gets hotter, it is harder for the body to keep its core temperature down.

BBC News· 22 Jun 2026
This entry
Level B2 · Upper Intermediate
Frequency Common
Updated