probability

noun

prob·​a·​bil·​i·​ty ˌprä-bə-ˈbi-lə-tē How to pronounce probability (audio)
plural probabilities
1
a(1)
: the chance that a given event will occur
(2)
: the ratio of the number of outcomes in an exhaustive set of equally likely outcomes that produce a given event to the total number of possible outcomes
b
: a branch of mathematics concerned with the study of probabilities
2
: something (such as an event or circumstance) that is probable
3
: the quality or state of being probable
4
: a logical relation between statements such that evidence confirming one confirms the other to some degree

Examples of probability in a Sentence

There is a low probability that you will be chosen. There is some probability of rain tomorrow. With the dark clouds moving in, rain seems more like a probability than a possibility. The probability of a coin coming up heads is one out of every two tries.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The Bayesian mathematical approach involves making inferences about probabilities based on available information. Beth C. Caldwell, The Conversation, 3 Apr. 2025 For example, there was a 15% probability of a recession in January and now that risk is 40%, Mark Zandi, Moody’s Analytics chief economist, told the Boston Globe. Peter Cohan, Forbes.com, 3 Apr. 2025 Finally, the researchers note that shingles diagnosis and treatment didn't increase the probability of dementia diagnoses. John Timmer, ArsTechnica, 3 Apr. 2025 These classifications indicate probability rather than frequency. Hannah Parry, MSNBC Newsweek, 3 Apr. 2025 See All Example Sentences for probability

Word History

First Known Use

15th century, in the meaning defined at sense 3

Time Traveler
The first known use of probability was in the 15th century

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Cite this Entry

“Probability.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/probability. Accessed 15 Apr. 2025.

Kids Definition

probability

noun
prob·​a·​bil·​i·​ty ˌpräb-ə-ˈbil-ət-ē How to pronounce probability (audio)
plural probabilities
1
: the quality or state of being probable
2
: something probable
3
a
: a measure of how often a particular event will happen if something which results in any of a number of possible events is done repeatedly
the probability of a coin coming up heads is ½
b
: a branch of mathematics concerned with the study of probabilities

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