English Reference
noun

equation

n.
US /ɪˈkweɪʒən/ UK /ɪkwˈeɪʒən/ equa·tion UK spelling equations

  1. 01 B1 Intermediate Math

    a mathematical statement that shows two amounts are equal using an equals sign (=).

    a formal statement of equality between two mathematical expressions, typically containing one or more variables.

    Simple

    The students spent the afternoon solving a difficult algebra equation.

    In context

    The physicist derived a complex differential equation to model the fluid dynamics of the cooling system.

    Usage

    Countable; often used with the verbs 'solve', 'balance', or 'derive'.

  2. 02 B2 Upper Intermediate

    a situation where you must consider several different things to find a solution or understand a problem.

    a complex situation or set of variables that must be balanced or considered as a whole.

    Simple

    Money is only one part of the equation when you are choosing a new job.

    In context

    When planning urban expansion, environmental preservation must remain a central part of the equation.

    Usage

    Often used in the phrase 'part of the equation'.

  3. 03 C1 Advanced Academic

    the act of treating two different things as if they are the same.

    the process of equating two or more elements or the state of being equal.

    Simple

    The equation of wealth with happiness is a common mistake in modern society.

    In context

    The author's simplistic equation of political dissent with treason was widely criticised by civil rights advocates.

  4. 04 C2 Proficiency Technical Science

    a small change made to a measurement to fix a regular error.

    a small correction applied to observed values to compensate for systematic errors or variations.

    Simple

    The scientist applied a time equation to the data to get a more accurate result.

    In context

    The equation of time accounts for the discrepancy between apparent solar time and mean solar time throughout the calendar year.

His fee, however, illustrates how quickly the equation can change once a teenager proves himself at senior level.

BBC News· 15 Aug 2026

Part of the equation remains what we cannot see: the chemistry within a team, the relationship with a specific coach, playing in a system that brings out the best in every player.

The Guardian· 20 Dec 2025

From Old French, from Latin aequātiō (“an equalizing”). Morphologically equate + -ion

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level C1 · Advanced
Frequency Common
Updated