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 New York City has a historical probability of only 11%. Jennifer Gray, CNN, "Dreaming of white Christmas this year? Keep dreaming," 24 Dec. 2019 And, of course, the Rockies and Sierra Nevada Mountains also consistently have a high probability of seeing a white Christmas. Billy Kobin, The Courier-Journal, "Dreaming of a white Christmas? Unfortunately, Louisville will be dry and warm," 19 Dec. 2019 Trying to bring a coastal feel to landlocked Denver has a high probability of ending with a dining room that feels like one big gimmick. Daliah Singer, The Know, "Review: This former food truck serves wild boar Cubans and kangaroo burgers in an old Berkeley auto shop," 13 Nov. 2019 Or a fiduciary financial planner will have access to software that models both investment and withdrawal scenarios designed to have the highest probability of making your money (and your spouse's) last your lifetime. Terry Savage,, "Informed choices can boost retirement income," 10 Oct. 2019 For example, Rs900 donation will count as three entries for the lottery and have a higher probability of getting picked in the draw. Ananya Bhattacharya, Quartz India, "A new fundraising site will let fans hang out with Varun Dhawan, Alia Bhatt—for a cause," 20 Aug. 2019 With two outs and two on, Josh Reddick hit a deep flyball to dead center field that, according to Statcast, had a 99 percent catch probability. Kyle Newman, The Denver Post, "Astros sweep Rockies as bats go flat and an outfielding misplay by Ian Desmond proves costly," 3 July 2019 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

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

22 Jan 2020

Cite this Entry

“Probability.” The Dictionary, Merriam-Webster Inc., Accessed 23 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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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).


out of the ordinary or unreasonable

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