# probability

## noun

prob·​a·​bil·​i·​ty
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 Fed rate speculation Markets have tempered expectations for a Federal Reserve interest rate cut in March following better-than-anticipated economic data, and now assign a 50% probability. Detroit Free Press, 11 June 2024 That is, the probability of the wanderer starting in neighborhood A and ending up in neighborhood B — the macroscale behavior — remains the same regardless of which streets within A or B the walker randomly traverses. Quanta Magazine, 10 June 2024 Traders scaled back their bets on more rate cuts this year, leaving the probability of reductions in September and December at about an even chance. Eshe Nelson, New York Times, 6 June 2024 For example, one way to represent words is to look at the probability that a word will appear next to another word, then another word and eventually all other words. The Physics Arxiv Blog, Discover Magazine, 30 May 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'probability.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

## 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

probability

## Cite this Entry

“Probability.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/probability. Accessed 23 Jun. 2024.

## Kids Definition

probability

noun
prob·​a·​bil·​i·​ty
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

## More from Merriam-Webster on probability

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