This is the 1677th most frequent Turkish word.
öğrencisi
"Öğrencisi" means "his/her/its student" or "the student of."
'Öğrencisi' here refers to a student associated with a specific institution (school in this case).
Ali bir okulun öğrencisidir.
Ali is a student of a school.
Here, 'öğrencisi' specifies a particular student within a given group (the math class).
Matematik dersindeki en başarılı öğrencisi Fatma'dır.
The most successful student in the math class is Fatma.
In this usage, 'öğrencisi' refers to an individual devoted to studying a subject (literature).