probability

noun

prob·​a·​bil·​i·​ty ˌprä-bə-ˈbi-lə-tē 

plural probabilities

1

a(1)

: the chance that a given event will occur

(2)

: the ratio of the number of outcomes in an exhaustive set of equally likely outcomes that produce a given event to the total number of possible outcomes

b

: a branch of mathematics concerned with the study of probabilities

2

: something (such as an event or circumstance) that is probable

3

: the quality or state of being probable

4

: a logical relation between statements such that evidence confirming one confirms the other to some degree

Synonyms

• likelihood

Examples of probability in a Sentence

There is a low probability that you will be chosen.

There is some probability of rain tomorrow.

With the dark clouds moving in, rain seems more like a probability than a possibility.

The probability of a coin coming up heads is one out of every two tries.

Recent Examples on the Web

The probability of lightning strikes rises as a thunderstorm approaches and peaks when the storm is directly above. —Nc Weather Bot, Charlotte Observer, 28 June 2025

The researchers even suggest there’s a 99.4% probability that the detection of these compounds wasn’t a fluke – a figure that, with repeat observations, could reach the gold standard for statistical certainty in the sciences. —Oliver Swainston, Space.com, 28 June 2025

More Clive Rose/Getty Images Now, the Mercedes team boss has revealed ahead of the Austrian Grand Prix qualifying session that the probability of Verstappen driving for Mercedes next year is very low, and that Russell and Andrea Kimi Antonelli will form the driver lineup for 2026. —Saajan Jogia, MSNBC Newsweek, 28 June 2025

It is arbitrarily chosen to be the 67% historical probability threshold... —Marshall Shepherd, Forbes.com, 28 June 2025

Word History

First Known Use

15th century, in the meaning defined at sense 3

Phrases Containing probability

• conditional probability
• in all probability
• probability density
• probability density function
• probability distribution
• probability function

Rhymes for probability

• affability
• audibility
• bistability
• capability
• changeability
• contractility
• credibility
• culpability
• disability
• disutility
• durability
• fallibility

Kids Definition

probability

noun

prob·​a·​bil·​i·​ty ˌpräb-ə-ˈbil-ət-ē 

plural probabilities

1

: the quality or state of being probable

2

: something probable

3

a

: a measure of how often a particular event will happen if something which results in any of a number of possible events is done repeatedly

the probability of a coin coming up heads is ½

b

: a branch of mathematics concerned with the study of probabilities