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

Money markets price in a 95% probability of a 25-basis-point ECB rate hike in September, according to LSEG, which would bring the deposit rate to 2.50%.

From The Wall Street Journal ● Aug. 21, 2026

Authorities say as the reservoir continues to dry up, there’s a higher probability that more skeletal remains will be discovered.

From Los Angeles Times ● Aug. 19, 2026

Markets currently price a 31% probability of a rate hike in September and a near 100% probability of a 25-basis point hike in December, according to LSEG.

From The Wall Street Journal ● Aug. 19, 2026

Telegram channels -- sifting through intelligence data -- close the information gap, putting out daily forecasts on the probability of different types of attacks.

From Barron's ● Aug. 16, 2026

“It’s a zero. There is zero probability that your default rate will be five percent.”

From "The Big Short" by Michael Lewis

On the balance of probabilities, she ruled that Daniel had died of a choking incident caused by his undiagnosed oesophageal cancer.

From BBC ● Aug. 24, 2026

Fundamental particles such as electrons are instead described by a "wavefunction," a mathematical representation that researchers can use to calculate the probabilities of properties such as position and momentum.

From Science Daily ● Aug. 24, 2026

But investing is a matter of probabilities, and the stock market in September has the lowest probability of gain of any throughout the year.

From MarketWatch ● Aug. 13, 2026

Some near-term positives remain, “with LNG demand at just over 18 Bcf a day and bargain hunting buyers believing upside value probabilities outweigh the downside at these price levels,” he adds.

From The Wall Street Journal ● Jul. 30, 2026

Another counter-intuitive problem involving seemingly disproportionate probabilities concerns a New York City man who has a woman friend in the Bronx and one in Brooklyn.

From "Innumeracy: Mathematical Illiteracy and Its Consequences" by John Allen Paulos

Related Words

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