If you’ve got no reason to skip school or work but you do it all the time anyway, you’ve go a bad case of absenteeism. When there's absenteeism, someone isn't showing up.
Absenteeism is a word for the habit of being absent. If you miss weeks of school, absenteeism has become a problem. Calling in sick to work every week is another example of absenteeism. Absenteeism can be like a contagious disease — sometimes entire schools have problems with absenteeism. If there’s a good excuse for the absence, like a serious illness, it’s not absenteeism. So don’t forget those doctor’s notes.