Unexpected time off, also known as unplanned leave, refers to an unforeseen absence from work that is not prearranged or scheduled. It occurs when an employee is unable to attend work due to unforeseen circumstances or emergencies.

Example
An employee wakes up feeling unwell and realizes they are unable to come to work due to illness. They notify their supervisor as soon as possible to inform them about their unexpected time off and provide any necessary updates regarding their condition and when they expect to return to work.