Event that can occur, but that cannot be predicted. It corresponds to a non-empty subset of the set of possible outcomes.

Synonym for possible event.

### Example

We are rolling an honest die with six faces numbered 1 to 6.

- Event A, which consists of rolling a number that is greater than 2, has 4 possible outcomes:

{3, 4, 5, 6}. - Event B, which consists of rolling a number that is less than 2, has 1 possible outcome:

{1}. - Event C, which consists of rolling a number that is less than 4, has 3 possible outcomes:

{1, 2, 3}. - Event D, which consists of rolling a number that is greater than 3, has 3 possible outcomes:

{4, 5, 6}.

Therefore, we can say that event A is more probable that event B, that event B is less probable than event A, and that events C and D are equally probable, since they have the same number of possible outcomes; they are equiprobables.