Absentees mean people who are not present, especially at work or school. Usually at schools and colleges, being absent for too many days might lead to failing a few classes, unless it is for any serious medical conditions. It is important for students to write a formal letter to the class teacher or the Head of the Department, in case they have been absent for a week or more.
In workplaces, however, the system works in a different way. If a person chooses to be absent for a day or more, they have to apply for leave beforehand from their superiors.
However, being an absentee all the time, in most events, might not lead to a very good reputation for a person as they might keep missing out on interesting events and programs.