"practice or habit of being absent," 1822, from absentee + -ism; originally in reference to landlords, especially in Ireland, who lived at a distance from their estates (the earlier word was absenteeship (1778) and Johnson's dictionary has absentee in the landlord sense). In reference to pupils or workers from 1922.
abscission
abscond
absence
absent
absentee
absenteeism
absent-minded
absinthe
absit omen
absolute
absolute zero