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



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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 This should include clear communication regarding what a prediction truly means, and what probability translates into in real-world terms. C. Brandon Ogbunu, Wired, "Yes, Accept the Flaws of Election and Epidemic Models," 10 Nov. 2020 On a video chat, Mahoney showed him a presentation detailing how certain decisions affected win probability. Ben Shpigel, New York Times, "Friday Night Bytes: Can Analytics Revolutionize High School Football?," 5 Nov. 2020 But the needle was ready to quickly update that probability. Dan Kopf, Quartz, "Why it’s okay to look at the New York Times “election needle”," 3 Nov. 2020 In 2000, several broadcast networks erroneously reported the Florida results, and in 2016, the New York Times’s election probability needle flopped dramatically from a sure-fire Democratic blue to a certain Republican red. Elise Taylor, Vogue, "How to Watch the Election Day Results, from Broadcast News Coverage to Free Livestreams," 2 Nov. 2020 Even sharp math students don’t always know much about statistics and probability. Michael Barone, WSJ, "‘Lost in a Gallup’ Review: Snapshots of the Electorate," 2 Nov. 2020 So even from a statistical probability standpoint, these viruses are more likely to come from bats than any other animals, because there are more bat species than many other broad types of animals. Jennifer Ouellette, Ars Technica, "Virus Hunters makes a strong case that COVID-19 is just the wake-up call," 1 Nov. 2020 First, assign a probability to various election disaster scenarios. Gleb Tsipursky, Fortune, "It may sound far-fetched, but businesses need to be ready for an election-related disaster," 29 Oct. 2020 Twice this year Atlanta has lost games in which ESPN put its win probability at better than 99%. Dave Birkett, Detroit Free Press, "Detroit Lions, Atlanta Falcons are the Kings of Collapse: No deficit or lead's safe with them," 25 Oct. 2020

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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Time Traveler for probability

Time Traveler

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

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Statistics for probability

Last Updated

15 Nov 2020

Cite this Entry

“Probability.” Dictionary, Merriam-Webster, Accessed 26 Nov. 2020.

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How to pronounce probability (audio)

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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