1.
younger sister (polite — referring to someone else's)
Polite term for the listener's or a third party's younger sister. The honorific さん makes it appropriate for talking about others; one's own younger sister is 妹 (without さん).
妹さんはお元気ですか。
Is your younger sister well?
妹さんは今、大学生ですか。
Is your younger sister a university student now?
妹さんが結婚されると聞いて、とても嬉しく思いました。
I was very glad to hear that your younger sister is getting married.
Polite reference form for someone else's younger sister — 妹 + the honorific suffix さん. Do not use for one's own younger sister when speaking to outsiders.
USAGE:
- Used when talking about the listener's or a third party's younger sister
- For one's own younger sister (to outsiders): 妹
- Within the family, older siblings call a younger sister by name, not by 妹さん
COMMON COLLOCATIONS:
- 妹さんはおいくつですか: How old is your younger sister?
- 妹さんによろしく: Say hi to your younger sister
- 妹さんとよく似ている: looks a lot like your younger sister
RELATED WORDS:
- 妹: one's own younger sister (humble; for outsiders)
- お姉さん: older sister (polite)
- 弟さん: someone else's younger brother (parallel form)