prob·​a·​bil·​i·​ty | \ ˌprä-bə-ˈbi-lə-tē How to pronounce probability (audio) \
plural probabilities

Definition of probability

1 : the quality or state of being probable
2 : something (such as an event or circumstance) that is probable
3a(1) : 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
(2) : the chance that a given event will occur
b : a branch of mathematics concerned with the study of probabilities
4 : a logical relation between statements such that evidence confirming one confirms the other to some degree

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Synonyms & Antonyms for probability


liability, likelihood


improbability, unlikelihood, unlikeliness

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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.
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Recent Examples on the Web

Temple is slightly favored, with a win probability of 51%. C.j. Doon,, "Can Maryland and Penn State preserve their ranked matchup? Most intriguing college football questions for Week 3," 13 Sep. 2019 Forecasters raised the probability of development -- and raised it again -- Wednesday morning for a tropical wave that is currently located on the other side of Florida in the Atlantic. Leigh Morgan, al, "Chances up to 60 percent that a tropical depression forms in the Gulf by next week," 11 Sep. 2019 The eight- to 14-day outlook has much of the country with a high probability of above average temperatures., "The warm weather isn’t going anywhere - The Boston Globe," 10 Sep. 2019 Analytics show the probability of making that field goal was much higher than moving the chains on fourth-and-long. David Haugh,, "Column: Placing the blame for Bears’ opening dud — Mitch Trubisky or Matt Nagy? — is less important than cleaning up the mess quickly," 11 Sep. 2019 The p-value, the probability of this happening by chance, was tiny: 0.001 per cent. Hannah Fry, The New Yorker, "What Statistics Can and Can’t Tell Us About Ourselves," 2 Sep. 2019 The professors also found the probability of a crisis was typically higher in global models than single-country models, illustrating the interdependency of national economies. Matthew De Silva, Quartz, "How do you predict the next financial crisis?," 28 Aug. 2019 Economists at Bank of America now think the probability of a restructuring next year is high, and that the recovery value of Argentina’s debt could be as low as 40%. The Economist, "Argentina faces the prospect of another default," 15 Aug. 2019 Earlier this week, scientists said the probability of another earthquake of magnitude 7 or greater resulting from the July 5 quake was less than 1%. Phil Willon,, "Ridgecrest earthquakes caused major damage at China Lake naval base," 12 July 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'probability.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of probability

15th century, in the meaning defined at sense 1

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Statistics for probability

Last Updated

15 Oct 2019

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Time Traveler for probability

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

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More Definitions for probability



English Language Learners Definition of probability

: the chance that something will happen
: something that has a chance of happening
: a measure of how often a particular event will happen if something (such as tossing a coin) is done repeatedly


prob·​a·​bil·​i·​ty | \ ˌprä-bə-ˈbi-lə-tē How to pronounce probability (audio) \
plural probabilities

Kids Definition of probability

1 : the chance of happening The probability of rain is low.
2 : something likely Rain is a probability.
3 : a measure of how likely a given event is The probability of a coin landing face up is ¹/₂.

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Comments on probability

What made you want to look up probability? Please tell us where you read or heard it (including the quote, if possible).


involving a confidence or trust

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