Translation guide
In Japanese, the word for 'sister' depends on whether you are talking about your own sister or someone else's, as well as the relative age (older or younger). There is no single neutral word that covers all cases.
Referring to your own older sister when speaking to family or in informal contexts.
Used to refer to your own older sister when talking to others. Not used to address her directly.
私の姉は医者です。
My older sister is a doctor.
Used to address your own older sister directly, or to refer to her within the family. Also used for other people's older sisters.
Casual, affectionate term for your own older sister, similar to 'big sis'.
Referring to your own younger sister when speaking to others.
Referring to someone else's older sister politely.
Referring to someone else's younger sister politely.
Referring to your own sisters collectively.
Means 'sisters' as a group. Can be used for your own sisters or sisters in general.
Referring to a nun or female member of a religious order.
Using 'sister' to refer to a close female friend, especially in solidarity.
Can be used metaphorically for a close bond, like 'sisterhood', but not commonly used as direct address.
姉 and 妹 are humble terms used only for your own family members. Using them for someone else's sister is rude. Use お姉さん or 妹さん instead.
お姉さんはお元気ですか。
How is your older sister?
When speaking directly to your older sister, use お姉さん or a casual variant like 姉ちゃん. For a younger sister, you usually just use her name. There is no common direct address equivalent to 'sis' for a younger sister.
姉妹 (しまい) means 'sisters' (female siblings). 兄弟 (きょうだい) means 'brothers' or 'siblings' in general, and can include sisters when the gender mix is unknown or mixed.
姉妹はいますか。
Do you have any sisters?
彼女は私にとって姉妹のような存在です。
She's like a sister to me.
お姉さん、ちょっと来て。
Sis, come here a sec.
姉ちゃん、それ取って。
Big sis, get that for me.
Used to refer to your own younger sister when talking to others. Not used to address her directly.
妹は大学生です。
My younger sister is a college student.
Polite way to refer to someone else's younger sister.
妹さんはお元気ですか。
How is your younger sister?
The standard polite term for someone else's older sister. Also used to address a young woman whose name you don't know.
田中さんのお姉さんに会いました。
I met Tanaka's older sister.
Very formal and respectful term for someone else's older sister, now mostly literary or historical.
姉上によろしくお伝えください。
Please give my regards to your older sister.
The standard polite term for someone else's younger sister.
妹さんは何歳ですか。
How old is your younger sister?
私には姉妹が二人います。
I have two sisters.
Loanword from English, used for Catholic nuns or in the context of sisterhood.
シスターは教会で祈っていました。
The sister was praying in the church.
Formal term for a nun.
彼女は修道女になりました。
She became a nun.
私たちは姉妹のようなものです。
We are like sisters.
In Japanese, calling a friend 'sister' directly is unnatural. Use their name with an appropriate suffix like さん or ちゃん, or a nickname.
ゆきちゃん、一緒に行こう！
Yuki, let's go together! (like 'sister' in a friendly way)