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

Their ability to use YES or NO shares priced between $0 and $1 directly translates to the probability of an event occurring in real time. —Gladys Louise Tyler, Forbes.com, 21 June 2026

Illinois and parts of Wisconsin, Iowa and Missouri are among the few states in NOAA's forecast that have an approximately 30% probability of being below the historical average temperature, which is created with data from 1991 to 2020. —Swasti Singhai, USA Today, 20 June 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, 19 June 2026

Their study found that southern portions of the San Andreas fault and parts of the adjacent San Jacinto fault line are locked and loaded to their highest stress levels in 1,000 years — increasing the probability of a significant earthquake. —Kasha Patel, CNN Money, 19 June 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