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

If power to the tuned mass damper failed (a plausible occurrence in a hurricane), this probability fell to once every 16 years. —Oscar Holland, CNN Money, 15 Aug. 2025

In an early-morning update on Friday, the agency said the disturbance at 50 percent chance of formation through 48 hours, with the same probability through seven days. —Joe Edwards, MSNBC Newsweek, 15 Aug. 2025

Apart from reducing the probability of ad fraud, white and blacklists enable greater brand safety since ads will not be delivered within inappropriate contexts. —Roman Vrublivskyi, Forbes.com, 12 Aug. 2025

Avid stargazers in the state have a 6.68% probability of seeing meteors or asteroids, the website said. —Hannah Poukish, Sacbee.com, 12 Aug. 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