What does probability mean?

Definitions for probability
ˌprɒb əˈbɪl ɪ tiprob·a·bil·i·ty

This dictionary definitions page includes all the possible meanings, example usage and translations of the word probability.

Princeton's WordNet

  1. probability, chancenoun

    a measure of how likely it is that some event will occur; a number expressing the ratio of favorable cases to the whole number of cases possible

    "the probability that an unbiased coin will fall with the head up is 0.5"

  2. probabilitynoun

    the quality of being probable; a probable event or the most probable event

    "for a while mutiny seemed a probability"; "going by past experience there was a high probability that the visitors were lost"


  1. probabilitynoun

    the state of being probable; likelihood

  2. probabilitynoun

    an event that is likely to occur

  3. probabilitynoun

    the relative likelihood of an event happening

  4. probabilitynoun

    a number, between 0 and 1, expressing the precise likelihood of an event happening

  5. Etymology: From probabilitas, from probabilis; see probable.

Samuel Johnson's Dictionary

  1. Probabilitynoun

    Likelihood; appearance of truth; evidence arising from the preponderation of argument: it is less than moral certainty.

    Etymology: probabilitas, Lat. probabilité, Fr. from probable.

    Probability is the appearance of the agreement or disagreement of two ideas, by the intervention of proofs, whose connection is not constant; but appears for the most part to be so. John Locke.

    As for probabilities, what thing was there ever set down so agreeable with sound reason, but some probable shew against it might be made? Richard Hooker, Preface.

    If a truth be certain, and thwart interest, it will quickly fetch it down to but a probability; nay, if it does not carry with it an impregnable evidence, it will go near to debase it to a downright falsity. Robert South, Sermons.

    Though moral certainty be sometimes taken for a high degree of probability, which can only produce a doubtful assent; yet it is also frequently used for a firm assent to a thing upon such grounds, as are fit fully to satisfy a prudent man. John Tillotson, Sermons.

    For a perpetual motion, magnetical virtues are not without some strong probabilities of proving effectual. John Wilkins.


  1. Probability

    Probability is the branch of mathematics concerning numerical descriptions of how likely an event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and 1, where, roughly speaking, 0 indicates impossibility of the event and 1 indicates certainty. The higher the probability of an event, the more likely it is that the event will occur. A simple example is the tossing of a fair (unbiased) coin. Since the coin is fair, the two outcomes ("heads" and "tails") are both equally probable; the probability of "heads" equals the probability of "tails"; and since no other outcomes are possible, the probability of either "heads" or "tails" is 1/2 (which could also be written as 0.5 or 50%). These concepts have been given an axiomatic mathematical formalization in probability theory, which is used widely in areas of study such as statistics, mathematics, science, finance, gambling, artificial intelligence, machine learning, computer science, game theory, and philosophy to, for example, draw inferences about the expected frequency of events. Probability theory is also used to describe the underlying mechanics and regularities of complex systems.


  1. probability

    Probability is a mathematical measure that quantifies the likelihood or chance of a particular event or outcome occurring. It is expressed as a number between 0 and 1, where 0 indicates that the event will not occur, and 1 indicates that the event is certain to occur. It is often expressed as a fraction, percentage, or decimal. Probability can be theoretical, based on reasoning and analysis, or empirical, based on observed data.

Webster Dictionary

  1. Probabilitynoun

    the quality or state of being probable; appearance of reality or truth; reasonable ground of presumption; likelihood

  2. Probabilitynoun

    that which is or appears probable; anything that has the appearance of reality or truth

  3. Probabilitynoun

    likelihood of the occurrence of any event in the doctrine of chances, or the ratio of the number of favorable chances to the whole number of chances, favorable and unfavorable. See 1st Chance, n., 5


  1. Probability

    Probability is a measure or estimation of how likely it is that something will happen or that a statement is true. Probabilities are given a value between 0 and 1. The higher the degree of probability, the more likely the event is to happen, or, in a longer series of samples, the greater the number of times such event is expected to happen. These concepts have been given an axiomatic mathematical derivation in probability theory, which is used widely in such areas of study as mathematics, statistics, finance, gambling, science, artificial intelligence/machine learning and philosophy to, for example, draw inferences about the expected frequency of events. Probability theory is also used to describe the underlying mechanics and regularities of complex systems.

U.S. National Library of Medicine

  1. Probability

    The study of chance processes or the relative frequency characterizing a chance process.

Suggested Resources

  1. probability

    The probability symbol -- In this Symbols.com article you will learn about the meaning of the probability symbol and its characteristic.

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British National Corpus

  1. Nouns Frequency

    Rank popularity for the word 'probability' in Nouns Frequency: #1885

How to pronounce probability?

How to say probability in sign language?


  1. Chaldean Numerology

    The numerical value of probability in Chaldean Numerology is: 5

  2. Pythagorean Numerology

    The numerical value of probability in Pythagorean Numerology is: 3

Examples of probability in a Sentence

  1. Clive Staples Lewis:

    We may not be able to get certainty, but we can get probability, and half a loaf is better than no bread.

  2. Abraham Lincoln:

    The probability that we may fail in the struggle ought not to deter us from the support of a cause we believe to be just.

  3. Captain Dave Carraro of FV-Tuna:

    We are going to stay out as long as we possibly can and we are going to fish as hard as we can, i think the other captains saw what we were doing and that was part of our success. The more time you spend out the water and have time more lines in the water and the higher probability you are going to get a bite, the higher probability you ’ll catch a fish.

  4. Davide Farnocchia:

    But we should keep in mind that the impact probability, overall is really small, in fact, there is a 99.94 % probability that there is not an impact trajectory. So, there is no particular reason for concern.

  5. Vannevar Bush:

    If scientific reasoning were limited to the logical processes of arithmetic, we should not get very far in our understanding of the physical world. One might as well attempt to grasp the game of poker entirely by the use of the mathematics of probability.

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Translations for probability

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"probability." Definitions.net. STANDS4 LLC, 2023. Web. 27 Sep. 2023. <https://www.definitions.net/definition/probability>.

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    boldly resisting authority or an opposing force
    • A. equivalent
    • B. defiant
    • C. occlusive
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