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

The effect comes from changes in the motion of electrons within their orbitals, regions around an atom's nucleus where electrons have a high probability of being located.

From Science Daily ● Sep. 18, 2026

Mitchell has frequently pushed his theory that players who can reach 1,000 PWR playing minutes a season "gives them a higher probability" of playing for the Red Roses.

From BBC ● Sep. 18, 2026

“When people say, ‘my probability of doom is x or y or whatever, it hits in a different way,” said Altman.

From MarketWatch ● Sep. 16, 2026

Having checked with industry players, MS analysts see only a low probability of regulators severely punishing Australia-listed Tuas over its breaches of license conditions.

From The Wall Street Journal ● Sep. 15, 2026

“Yes. My daemon’s tongue can taste probability, you know.”

From "The Golden Compass" by Philip Pullman

Risk is when you know the possibilities and the probabilities.

From MarketWatch ● Sep. 15, 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

Actuarial analysis, consideration of historical performance and precedent, trend analysis, Monte Carlo scenario modeling and the like help determine probabilities so an investor can calculate the “excess” return required to compensate for a risk.

From The Wall Street Journal ● Sep. 8, 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

Pascal’s wager on God’s existence, for example, can be cast as a choice between the relative probabilities and consequences of Type I and Type II errors.

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

Related Words

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