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

But while the civil court found the war crimes allegations were mostly proven on a balance of probabilities, the war crime murder charges would have to be proved in a criminal court to a higher standard of beyond reasonable doubt. —ABC News, 17 Apr. 2026

Markets are pricing in a 100% probability that the committee stays on hold again at its April 28-29 meeting, and in fact do not expect any cuts this year. —Jeff Cox, CNBC, 16 Apr. 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, 16 Apr. 2026

The information about trending patterns is useful to those who manage risk based on probabilities, but is of less importance to the rest of us. —Dinah Voyles Pulver, USA Today, 15 Apr. 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