# constant

/ˈkɑnstənt/ (US) · /kˈɒnstənt/ (UK)

Source: https://englishreference.com/word/constant
Updated: 2026-08-15

## Senses

### 1. happening all the time

adjective · CEFR B2

happening again and again or staying the same for a long time.

For teachers: occurring continuously or recurring frequently over a period of time.

- The constant noise from the construction site made it hard to sleep.
- The project was delayed by constant interruptions and a lack of clear leadership from the department head.

### 2. unchanging

adjective · CEFR B2 · Academic

staying at the same level, speed, or value.

For teachers: remaining invariant or unchanging in nature, value, or intensity.

- The pilot maintained a constant speed throughout the flight.
- Maintaining a constant temperature is critical for the success of this chemical reaction.

### 3. a fixed value

noun · CEFR C1 · Academic · Technical

a number or value that does not change during a calculation or experiment.

For teachers: a quantity or parameter that does not change its value throughout a given mathematical operation or scientific discussion.

- In this math problem, 'g' represents the constant for gravity.
- The researcher identified the atmospheric pressure as a constant to simplify the initial stages of the simulation.

### 4. programming identifier

noun · CEFR C1 · Technical

a name in computer code that represents a value that cannot be changed while the program is running.

For teachers: an identifier bound to an invariant value, used in source code to improve readability and prevent accidental modification.

- The programmer defined the maximum number of users as a constant.
- By using a constant for the API endpoint, the developers ensured that the URL remained consistent across the entire application.

Usage: In many programming languages, constants are written in ALL_CAPS by convention.

## Examples

- The speed of light is a physical constant.
- In this computer program, the user's ID number is a constant that cannot be edited after registration.
- While the variables in the experiment were adjusted daily, the temperature of the laboratory remained a constant to ensure the validity of the results.

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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.