poor student; underachiever
Refers to a student who performs poorly academically or is ranked low in a class. Often used in contrast with 優等生 (honor student). Can carry a slightly negative or self-deprecating tone.
彼は自分を劣等生だと思っている。
He thinks of himself as a poor student.
劣等生だった彼が、努力して成績を上げた。
He was an underachiever, but he worked hard and improved his grades.
劣等生 is a neutral, formal term for a poorly-performing student, whereas 落ちこぼれ is colloquial and carries a stronger, more sensitive negative connotation.
優等生 is a top, exemplary student, while 劣等生 is a poor or struggling student.
Compound of 劣等 (inferior, low grade) and 生 (student). The exact historical derivation is uncertain, but the word follows a common pattern for describing types of students.