probability

American  

[prob-uh-bil-i-tee] / ˌprɒb əˈbɪl ɪ ti /

noun

• probabilities
  plural

1. the quality or fact of being probable.

2. a strong likelihood or chance of something.

   The probability of the book's success makes us optimistic.

3. a probable event, circumstance, etc..

   Our going to China is a probability.

4. Statistics.

   1. the relative possibility that an event will occur, as expressed by the ratio of the number of actual occurrences to the total number of possible occurrences.

   2. the relative frequency with which an event occurs or is likely to occur.

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idioms

1. in all probability, very probably; quite likely.

   The factory will in all probability be relocated.

probability British  

/ ˌprɒbəˈbɪlɪtɪ /

noun

1. the condition of being probable

2. an event or other thing that is probable

3. statistics a measure or estimate of the degree of confidence one may have in the occurrence of an event, measured on a scale from zero (impossibility) to one (certainty). It may be defined as the proportion of favourable outcomes to the total number of possibilities if these are indifferent ( mathematical probability ), or the proportion observed in a sample ( empirical probability ), or the limit of this as the sample size tends to infinity ( relative frequency ), or by more subjective criteria ( subjective probability )

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probability Scientific  

/ prŏb′ə-bĭl′ĭ-tē /

1. A number expressing the likelihood of the occurrence of a given event, especially a fraction expressing how many times the event will happen in a given number of tests or experiments. For example, when rolling a six-sided die, the probability of rolling a particular side is 1 in 6, or 1/6.

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probability Cultural  

1. A number between zero and one that shows how likely a certain event is. Usually, probability is expressed as a ratio: the number of experimental results that would produce the event divided by the number of experimental results considered possible. Thus, the probability of drawing the ten of clubs from an ordinary deck of cards is one in fifty-two (1:52), or one fifty-second.

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probability More Idioms  

1. see in all probability.

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Other Word Forms

Derived Forms

• nonprobability
  noun
• superprobability
  noun

Inflected Forms

Nouns

• probabilities
  plural

Etymology

Origin of probability

From the Latin word probābilitās, dating back to 1545–55. See probable, -ity

Explanation

Probability has to do with how likely something is to happen. If there's a 50/50 chance, then the probability is 50%. Probability is a part of math involving percentages and chance. The probability of a thing happening is the same as the odds or chances of something happening. When you watch a weather forecast, it might say there's a 30% chance of showers; that's probability. Gambling — on sports or something else — is also based on probability. Since most things in life are uncertain, it's helpful to know if the probability is high or low for things you want to do or try.

Example Sentences

See Examples For:

probability probabilities

There’s also an 83% chance that this El Niño will be the strongest on record, which goes back to 1950, up from a 75% probability forecast last month.

From Los Angeles Times ● Oct. 10, 2026

On Thursday, NOAA’s Climate Prediction Center said the chance of a historic, record-breaking El Niño is now 83%, up from the probability of 75% issued last month.

From Los Angeles Times ● Oct. 8, 2026

Investors priced a 23% probability of a quarter-point Fed rate increase on Oct.

From The Wall Street Journal ● Oct. 6, 2026

Effectively closing the U.S. market to Chinese humanoids “improves the probability that a Western humanoid ecosystem develops successfully,” according to Citi analyst Ross MacDonald.

From MarketWatch ● Oct. 2, 2026

By the time Victoria was seventeen, and Tristran also, she was in all probability, he was certain, the most beautiful girl in the British Isles.

From "Stardust" by Neil Gaiman

The two movements overlap heavily in membership and ideas, sharing an emphasis on reasoning through evidence and probabilities, and a conviction that preventing human extinction should be a top priority.

From Barron's ● Oct. 2, 2026

Furthermore, Gabaix told me in an email, these miniscule probabilities apply to any month; there is nothing special about October.

From MarketWatch ● Sep. 18, 2026

Adapted for TV: There will be the use of augmented reality, athlete headshots, win probabilities and projected finishing positions to develop viewer experience.

From BBC ● Sep. 11, 2026

Softer inflation readings in June and July had eased pressure on the Fed to raise rates in September, with market-implied probabilities of a hike falling below 40% earlier this month.

From The Wall Street Journal ● Aug. 28, 2026

But shifting probabilities could be ignored, until the plane did or did not arrive.

From "The Big Short" by Michael Lewis

Related Words

• anticipation
• chance
• contingency
• expectation
• feasibility
• odds
• possibility
• prospect