A more thorough explanation:

An exeat is permission to leave a certain place. For example, a school might give a student an exeat to leave campus for a doctor's appointment. It can also refer to permission that a bishop gives to a priest to leave their diocese.

Examples:

• John received an exeat from his teacher to leave school early for a dentist appointment.
• The bishop granted an exeat to the priest to attend a conference in another diocese.

These examples show how an exeat is permission to leave a certain place, whether it's a school or a diocese.