English Reference
noun

approximation

n.
US /əˌpɹɑksəˈmeɪʃən/ UK /ɐpɹˌɒksɪmˈeɪʃən/ ap·prox·i·ma·tion UK spelling approximations

  1. 01 B2 Upper Intermediate Math

    a value or amount that is nearly correct but not exact.

    a value or quantity that is nearly but not exactly correct, often used when precise measurement is impossible or unnecessary.

    Simple

    The figure of ten thousand dollars is just a rough approximation of the total cost.

    In context

    For the purposes of the initial budget proposal, a rough approximation of the overhead costs will suffice until the audit is complete.

    Usage

    Often used with the adjectives 'rough', 'close', or 'near'.

    estimateestimationrough calculation
    exactnessprecision
  2. 02 C1 Advanced Academic

    something that is similar to another thing but not exactly the same.

    a thing that is similar to something else, typically a less perfect or less complete version.

    Simple

    His latest painting is a close approximation of the style used by the old masters.

    In context

    The simulated environment provides a functional approximation of deep-sea conditions, allowing researchers to test equipment without the risks of actual deployment.

    Usage

    Frequently followed by the preposition 'of'.

  3. 03 C1 Advanced Technical Science

    the act of coming close to a result or value.

    the process of approaching a value, state, or condition through successive stages of increased accuracy.

    Simple

    The scientist used a method of approximation to find the answer to the complex problem.

    In context

    The algorithm relies on successive approximation to reach a stable solution within the specified margin of error.

Since each thunderquake is going to be unique due to the different locations and conditions, this model is going to be, at best, an approximation.

Ars Technica· 21 Aug 2026

Depending on the desired precision, we can systematically improve our formulas using additional approximation methods," says Florian Ecker from TU Wien.

ScienceDaily· 30 Aug 2026

Etymology tree Proto-Indo-European *h₂éd Proto-Italic *ad Proto-Italic *ad- Latin ad- Latin proximō Latin approximō Latin approximātusder. Middle English approximat English approximate Proto-Indo-European *-tisder. Proto-Italic *-tjō Latin -tiō Latin -ātiōlbor. Old French -ationbor. Middle English -acioun English -ation English -ion English approximation From approximate + -ion.

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

This entry
Level C1 · Advanced
Frequency Frequent
Updated