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probability

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

noun

plural

probabilities

  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.

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 )

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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.

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.

probability More Idioms  

  1. see in all probability.

Other Word Forms

  • nonprobability noun
  • superprobability noun

Etymology

Origin of probability

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

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Distillation involves training a weaker model to mimic the probability distributions of a more powerful model, often through analyzing millions of API responses to reverse engineer the “logic” behind the model’s intelligence.

From MarketWatch

Market odds of Fed officials keeping rates steady at the March meeting are around 96%, but by July, the probability is more of a 50/50 shot.

From Barron's

Odds of Fed officials keeping rates steady are around 96%, but by July, the probability is more of a 50/50 shot.

From Barron's

Prediction markets allow participants to bet on the outcome of future events, with prices shifting to reflect probability.

From The Wall Street Journal

Our recommendations support the use of probabilities instead of dichotomous “p-values” and the inclusion of findings from related studies to evaluate safety and effectiveness—an invaluable advancement for rare-disease research.

From The Wall Street Journal

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.