noun
student of a girls' school
Refers specifically to a student attending a girls' school (女子校). Not a general term for female high school students.
彼女は有名な女子校生だ。
She is a student at a famous girls' school.
女子高生 is a more common term for a female high school student, regardless of whether the school is co-ed or girls-only. 女子校生 specifically implies attendance at a girls' school.
女子生徒 is a general term for a female student (elementary through high school). 女子校生 narrows the context to a girls' school.
Compound of 女子校 (joshi-kō, 'girls' school') and 生 (-sei, 'student').