probability

noun
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

Synonyms

liability, likelihood

Antonyms

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

Neither the weather service nor the Storm Prediction Center think a tornado watch for Alabama will be needed, as the overall probability of tornadoes is too low. Leigh Morgan, al.com, "‘Conditional’ threat for isolated tornadoes overnight in central Alabama," 6 June 2019 Yogurt, milk, and cheese in particular neutralize stomach acid and bile acid, increasing the probability that probiotics will reach the intestines. Beth Janes, Good Housekeeping, "Everything You Need to Know About Probiotics, According to Experts," 11 May 2019 But a variety of analysis methods suggested that there was an additional signal at 233 days, with a false alarm probability of only one in 1015. John Timmer, Ars Technica, "Sun’s closest solo star may have company," 14 Nov. 2018 The date with the highest probability is Aug. 13, at 19 percent. Weldon B. Johnson, azcentral, "Rain in Phoenix on June 11? That would be a first," 11 June 2018 Remaining haters can soothe themselves with the probability that the Cavaliers will fall short for the third time in four years, and James’s finals ledger will soon read 3 rings in 9 tries, as opposed to Michael Jordan’s perfect 6-0. New York Times, "Look Who Answered LeBron’s Call: Jeff Green, the Former Celtic," 28 May 2018 That’s the third-highest probability of any team in the tournament. Fortune, "UBS Predicts 2018 World Cup Winner After 10,000 Simulations," 17 May 2018 The start of Endymion coincides with the highest probability for heavy rain in the city. Greg Larose, NOLA.com, "Endymion Saturday weather: See the forecast, parade by parade through the day," 10 Feb. 2018 So that’s why OpenAI was created as a nonprofit foundation, to ensure that AI power ... or to reduce the probability that AI power would be monopolized. Eric Johnson, Recode, "Full Q&A: Tesla and SpaceX CEO Elon Musk on Recode Decode," 2 Nov. 2018

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

11 Jun 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

probability

noun

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

probability

noun
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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