弟弟，小弟，小兄弟

1. younger brother, little brother, kid brother

noun (common) (futsuumeishi)

姐夫/妹夫（配偶的弟弟或妹妹的丈夫）

2. brother-in-law (spouse's younger brother or younger sister's husband)

noun (common) (futsuumeishi)

学生，学徒

3. pupil, apprentice

noun (common) (futsuumeishi) archaic