This is the 12142nd most frequent Turkish word.
gözbebeği
"Pupil" (the central part of the eye) or "apple of one's eye" (metaphorically, something cherished).
Here, 'gözbebeği' refers to the anatomical term meaning 'pupil.'
Gözbebeği, insanın gözündeki en hassas noktadır.
The pupil is the most sensitive part of a person's eye.
In this sentence, 'gözbebeği' is used metaphorically to mean 'someone cherished.'
O, anne babasının gözbebeğiydi.
He/She was the apple of his/her parents' eye.
Here, 'gözbebeği' denotes 'something that one holds very dear.'