# kernel

/ˈkɝnəɫ/ (US) · /kˈɜːnəl/ (UK)

Source: https://englishreference.com/word/kernel
Updated: 2026-06-20

## Senses

### 1. seed or nut

noun · CEFR B2

the inner part of a nut or a single grain of corn.

For teachers: the inner, usually edible part of a nut or fruit stone, or a single whole grain of a cereal plant.

- The squirrel cracked the hard shell to reach the sweet kernel inside.
- The recipe calls for toasted pine nut kernels, which provide a rich, buttery texture to the pesto sauce.

### 2. core idea

noun · CEFR C1 · Formal

the most important part of an idea or a story.

For teachers: the central or essential part of a concept, plan, or story around which other details are built.

- There was a kernel of truth in his strange story.
- While the initial proposal was flawed, it contained a kernel of brilliance that the design team eventually developed into a successful product.

### 3. computing

noun · CEFR C1 · Technical

the most important part of a computer's software that controls the hardware.

For teachers: the fundamental part of an operating system that manages system resources and communication between hardware and software.

- The computer crashed because of a serious error in the kernel.
- Updating the Linux kernel can improve system performance and provide better support for new hardware components.

Usage: Usually used with 'the' in a singular sense.

### 4. mathematics

noun · CEFR C2 · Technical

a special set of numbers or values in a mathematical function.

For teachers: the set of elements in the domain of a function that are mapped to the identity element or zero.

- The professor asked the students to find the kernel of the linear transformation.
- In linear algebra, the kernel of a matrix represents the solutions to the homogeneous system of equations.

## Examples

- The squirrel ate the soft kernel inside the nut.
- There was a kernel of truth in his story, even though most of it was made up.
- The operating system's kernel manages the communication between the software applications and the hardware, ensuring that system resources are allocated efficiently and securely.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.