English Reference
noun

coefficient

n.
US /ˌkoʊəˈfɪʃənt/ UK /kˌəʊɪfˈɪʃənt/ co·ef·fi·cient UK spelling coefficient's, coefficient's

  1. 01 C1 Advanced AcademicTechnical Math

    a number that you multiply a variable by in a math problem.

    a constant factor by which an algebraic term or variable is multiplied.

    Simple

    In the equation 5x, the number 5 is the coefficient of x.

    In context

    The student struggled to isolate the variable because they had incorrectly identified the negative coefficient during the first step of the calculation.

    Usage

    Usually placed immediately before the variable it modifies.

    Teacher's tip

    While common in algebra, this is a high-level academic word that students will mostly encounter in STEM contexts.

  2. 02 C1 Advanced AcademicTechnical Science

    a number that measures a specific quality of a material or process.

    a numerical value or ratio that serves as a measure of a specific physical property or characteristic under defined conditions.

    Simple

    The coefficient of friction tells us how easily an object slides on a surface.

    In context

    Engineers must calculate the expansion coefficient of the metal to ensure the bridge can withstand extreme temperature fluctuations without warping.

    Usage

    Often used in the pattern 'coefficient of [property]'.

    Teacher's tip

    In this context, the word describes a fixed physical property rather than a variable multiplier.

Usage negative coefficient · positive coefficient

The maximum condensation heat transfer coefficient, which measures a surface's ability to transfer heat, reached approximately 88 kW·m -2 ·K -1 .

ScienceDaily· 23 Aug 2026

The researchers found a characteristic λ-shaped anomaly in the material's thermal expansion coefficient near 1,590 Kelvin, a signature of phase transitions that has also been observed in other superionic materials.

Phys.org· 21 Aug 2026

From French coefficient. Coined by French mathematician François Viète. Or influenced by (New) Latin coefficient-, which is the stem of coefficiens, which is a substantivation of the present active participle of coefficio, which comes from co- and efficio.

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

This entry
Level C1 · Advanced
Frequency Frequent
Updated