const

IPA/kˈɒnst/
IPA/kˈɑːnst/

const — noun

1. a written abbreviation for 'constant', used in computing to label a value or var

1.nounB1
Definition

a written abbreviation for 'constant', used in computing to label a value or variable that the programmer does not intend to change while a program runs.

Example

Haruto declared a const variable for the sales tax rate in the code.

const + variable/noun for a fixed value in code

Using const helps other programmers see which values should stay the same.

Common collocations
  • const variable
  • const value
  • declare const
  • mark with const
Synonyms
  • final

    used in Java for the same purpose; more common in OOP contexts

  • readonly

    used in C# and TypeScript; allows assignment only at declaration or in a constructor

Antonyms
  • variable

    a value that can change; var or let in many languages

Usage Note

In many programming languages such as C++, JavaScript, and Rust, 'const' is a keyword written in lowercase. It is typically placed before a variable declaration to signal that the variable's value cannot be reassigned after initial assignment.

Common Mistakes

I declared a const variable and later changed its value in the code.
I declared a const variable, so the compiler prevents me from changing its value.
Changing the value of a const variable causes an error in most languages.

2. a written abbreviation for 'constitution' or 'constitutional', used in legal wri

2.nounB2
Definition

a written abbreviation for 'constitution' or 'constitutional', used in legal writing and official documents to refer to a country or state's founding legal document.

Example

The judge referred to Article V of the U.S. Const. during the hearing.

Const. with period + Article [number] + of

Gabriela found the relevant clause in the state const. after searching for an hour.

Common collocations
  • U.S. Const.
  • Const. of
  • state const.
  • under the const.

Usage Note

When written with an initial capital letter and a period (Const.), it almost always refers to a specific constitution. Used informally within legal case citations and academic footnotes.

3. a written abbreviation for 'construction', used in project plans, signs, and eng

3.nounB1
Definition

a written abbreviation for 'construction', used in project plans, signs, and engineering documents to refer to the process of building or assembling something.

Example

The const. of the new hospital wing is scheduled to finish in March.

const. of + [building/infrastructure project]

Ravindra checked the const. schedule before ordering the steel beams.

Common collocations
  • under const.
  • const. of
  • const. schedule
  • delays in const.

Usage Note

Common on roadside signs ('Under Const.'), in architectural blueprints, and in civil engineering reports. The full form 'construction' is more common in everyday writing.

4. a written abbreviation for 'constant', used in mathematics and science to refer

4.nounB1
Definition

a written abbreviation for 'constant', used in mathematics and science to refer to a quantity or number that remains the same across all situations or calculations.

Example

The speed of light is a well-known const. in physics equations.

const. as a label for a mathematical/scientific invariant

Aylin wrote the value of const. π on the board for the geometry class.

Common collocations
  • const. in physics
  • mathematical const.
  • list a const.
  • known const.
Synonyms
  • invariant

    more formal; used in advanced mathematics and computer science

Antonyms
  • variable

    a quantity that can change in an equation or experiment

Usage Note

Used in textbooks, scientific papers, and mathematical proofs to save space. Unlike the programming sense (const keyword), this sense always refers to the underlying invariant value itself, not to a language keyword.

Common Mistakes

The value of const π is 3.14 in this experiment.
The value of the constant π is 3.14 in this experiment.
When speaking or writing formally, use the full word 'constant' instead of the abbreviation.

Word family

Synonym discussion

Sense: noun/1

All three terms label values that should not change in programming, but they belong to different languages. 'const' is the general-purpose keyword in C, C++, and JavaScript — it is the most widely recognised and appears in the oldest code bases. 'final' is the Java equivalent and carries the same meaning, but Java developers never use 'const' for this purpose, so learners moving between languages must switch terms. 'readonly' appears in C# and TypeScript and is slightly more flexible: a readonly field can be assigned at declaration or inside a constructor, whereas a const value in C++ or JavaScript must be set at the point of declaration. In everyday usage, 'const' is what most programmers reach for first, while 'final' and 'readonly' are language-specific alternatives that mean the same thing for practical purposes.

const ↗final ↗readonly

Common collocations

Nouns

  • const value
  • const variable
  • const schedule
  • U.S. Const.

Phrases

  • mark with const
  • delays in const.

Prepositions

  • const. of
  • under const.

Etymology

LatinFrenchEnglish

'Const' is a shortened form of the English word 'constant', which comes from the Latin 'constantem' (meaning 'standing firm' or 'unwavering'). The abbreviation has been used in technical and legal writing since at least the 19th century to save space in notes, tables, and citations. Its modern use as a programming keyword dates from the 1970s when the C language introduced 'const' as a type qualifier.