This is the 10772nd most frequent Turkish word.
defter
Notebook.
Here, 'defter' refers to a notebook, commonly used to write notes or assignments.
Defterime ödevlerimi yazıyorum.
I am writing my assignments in my notebook.
In this sentence, 'defter' again means a notebook, indicating an item purchased for usage.
Mağazadan yeni bir defter aldım.
I bought a new notebook from the store.
Here, 'defter' is used to describe decorative or special notebooks, often bought as gifts.