noun / adjective
truant
TROO-uhnt/trˈuʌnt/
Absent without permission, especially from school, or a student who is so absent.
The truant student leaves while the teacher gestures for her to return.

Etymology
The word first described a beggar or vagabond, then someone who wandered from an appointed place or shirked responsibilities. That later sense became especially associated with children staying away from school without permission.
In context
… what you truly have there is a truant and what you truly need to be doing is finding out why that child doesn't want to attend school …
More examples
- He was marked truant after leaving without permission.
- The novel follows two truants who skip class together.
- A counselor met with the frequent truant.
Forms
truant · truants
truancy noun — absence without permission, especially from school
Similar words
- absentee
- An absentee is not present; a truant lacks permission for the absence.
- school skipper
- School skipper informally describes the same conduct; truant is the more formal institutional term.