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 At -142 on the moneyline, the Steelers implied probability to win is 59 percent. Jeremy Cluff, azcentral, "Arizona Cardinals vs. Pittsburgh Steelers picks, predictions: Who wins Week 14 NFL game?," 4 Dec. 2019 The twin trends — an increased probability of death in midlife and a population-wide reversal of longevity — set the U.S. in stark contrast to every other affluent country in the world. Melissa Healy,, "Suicides and overdoses among factors fueling drop in US life expectancy," 3 Dec. 2019 Law enforcement is thinking about the probabilities. Clara Turnage, Arkansas Online, "Activist, police in Little Rock focus on missing people," 28 Nov. 2019 Attempting the field goal lowered the win probability to 16.7 percent. Mike Finger,, "Finger: For Cowboys’ Jason Garrett, Longhorns’ Tom Herman, smarts ceding to stubbornness," 27 Nov. 2019 And what are the probabilities that anyone fighting back against unsanctioned police violence could be thought of as anything beyond a thug or a murderer by the greater public? Jelani Cobb, The New Yorker, "The Powerful Perspective of “Queen & Slim”," 27 Nov. 2019 In the most recent CNBC Fed Survey of fund managers, economists and strategists, respondents gave a 34 percent probability that the U.S. will slide into recession in the next year. NBC News, "Consumer confidence falls for third straight month, as trade war continues," 29 Oct. 2019 Part of the problem is that our brains have trouble precisely computing probabilities without appropriate training. Karthik Kannan, The Conversation, "How can we make sure that algorithms are fair?," 16 Dec. 2019 To do so would mean halving all carbon emissions by 2030, which is, in all probability, not going to happen. Jennifer Wright, Harper's BAZAAR, "The Eco-Fascists Are Coming," 10 Dec. 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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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

8 Jan 2020

Cite this Entry

“Probability.” The Dictionary, Merriam-Webster Inc., Accessed 18 January 2020.

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More Definitions for probability


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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