English Reference
noun

probability

n.
US /ˌpɹɑbəˈbɪɫəˌti/ UK /pɹˌɒbəbˈɪlɪti/ prob·a·bil·i·ty UK spelling probabilities

  1. 01 B2 Upper Intermediate

    the chance that something will happen or is true.

    the quality or state of being probable; the extent to which something is likely to happen.

    Simple

    There is a high probability of rain this afternoon, so take an umbrella.

    In context

    The probability of a successful merger remains high, provided that both boards agree on the final valuation by the end of the quarter.

    Pitfall
    There is a high probability for rain today. There is a high probability of rain today.

    Use the preposition 'of' after probability to indicate what event is likely to happen.

  2. 02 B2 Upper Intermediate Technical Math

    a number between 0 and 1 that shows exactly how likely something is.

    a precise numerical measure of the likelihood of an event, where 0 indicates impossibility and 1 indicates certainty.

    Simple

    In this game, the probability of drawing a red card is exactly fifty percent.

    In context

    The algorithm calculates the probability of each outcome based on historical data sets and real-time variables.

    Usage

    Often used with 'of' followed by a gerund or noun phrase.

  3. 03 C1 Advanced Formal

    something that is very likely to happen.

    a probable event or outcome; something that can reasonably be expected to occur.

    Simple

    A change in the law is now a strong probability rather than just a hope.

    In context

    While a total market collapse is unlikely, a period of stagnation is a distinct probability that investors must prepare for.

Usage highly probability · increase probability · reduce probability

If you stick you will win in 1000 trials, a win probability of 2/3, and if you switch you will win in 500 trials, a win probability of 1/3.

The Guardian· 17 Aug 2026

Most public health scientists believed that nature was the only important “bioterrorist” , based simply on prior probabilities.

The Guardian· 15 Aug 2026

From Middle French probabilité, from Latin probābilitās (“probability, credibility”), from probābilis (“probable, credible”).

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

This entry
Origin Latin probābilitās
Level B2 · Upper Intermediate
Frequency Common
Updated