probability

[prob-uh-bil-i-tee]

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.

probability

/ 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 )

probability

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

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.

Other Word Forms

• nonprobability noun
• superprobability noun

Word History and Origins

Origin of probability¹

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

Idioms and Phrases

Idioms

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

   The factory will in all probability be relocated.

see in all probability.

Example Sentences

Traders in financial markets see a 96% probability of a rate cut this month.

Read more on MarketWatch

Investors are increasingly turning to Polymarket for fast-changing probabilities that its bettors assign to future events, such as election results or the length of the government shutdown.

Read more on Wall Street Journal

The probability of precipitation is most likely on Tuesday and Wednesday, occurring mostly east and north of L.A.

Read more on Los Angeles Times

“With this funding I would be able to adjust the operations of the hospital without being disruptive and have the highest probability of success,” Flanigan said.

Read more on Los Angeles Times

The probability of another second row emulating Eales' feat and winning a crucial match against New Zealand has always seemed unlikely, but that could change in Bristol on Friday.

Read more on BBC

Related Words

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