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 of probability

• 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

That’s why Rosengren, UCSD colleagues Thomas Bewley and Ben Hanson, and colleagues at the University of Arizona are investigating rare, low-probability chances for destruction, thereby offering authorities the best advice on when to launch deflection missions. —New Atlas, 10 May 2026

In fact, Yardeni hiked the probability that the Roaring 2020s will continue to 80% from 60% simply by merging it with his meltup scenario, which had 20% odds. —Jason Ma, Fortune, 10 May 2026

The probability of lightning strikes rises as a thunderstorm approaches and peaks when the storm is directly above. —Star-Telegram Weather Bot, Fort Worth Star-Telegram, 10 May 2026

Coaches know the probability of scoring off a slot-line sequence. —Fluto Shinzawa, New York Times, 9 May 2026

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