This is the 4423rd most frequent Dutch word.
casier
Locker or pigeonhole.
In this sentence, 'casier' means 'locker', representing a place for storage such as at a school or gym.
Ik legde mijn boeken in de casier.
I put my books in the locker.
Here, 'casier' again refers to 'locker', illustrating its use in possession and storage context.
De casier van de leerling zat vol papieren.
The student's locker was full of papers.
In this usage, 'casier' describes a personalized storage locker provided for employees.