兄

Usage

兄 (あに) is the humble noun for your own older brother when you talk to people outside the family. For someone else's older brother, and when you call or refer to your own brother inside the family, use お兄さん (おにいさん); お兄ちゃん (おにいちゃん) is the affectionate form. Counting siblings uses 人 with いる: 兄が一人います.

The sibling system

• 兄 (あに) / お兄さん (おにいさん): older brother
• 姉 (あね) / お姉さん (おねえさん): older sister
• 弟 (おとうと) / 弟さん (おとうとさん): younger brother
• 妹 (いもうと) / 妹さん (いもうとさん): younger sister
• 兄弟 (きょうだい): siblings in general; 姉妹 (しまい): sisters

Notice that younger siblings have no お〜さん form: 弟さん and 妹さん already refer to another person's.

Examples

• 兄は東京の会社で働いています。 あに は とうきょう の かいしゃ で はたらいています。 My older brother works at a company in Tokyo.
• 私には兄が一人と妹が一人います。 わたし に は あに が ひとり と いもうと が ひとり います。 I have one older brother and one younger sister.
• 田中さんのお兄さんは医者です。 たなかさん の おにいさん は いしゃ です。 Tanaka's older brother is a doctor.
• お兄ちゃん、一緒に行こう。 おにいちゃん、 いっしょ に いこう。 Big brother, let's go together.

Traps for Spanish, English and French speakers

• There is no plain word for brother. hermano, frère and brother say nothing about age; Japanese forces a choice between 兄 (older) and 弟 (younger). ‘Tengo un hermano’ cannot be translated until you know who was born first. The umbrella word is 兄弟 (きょうだい), which covers siblings of either sex.
• 兄 vs お兄さん is about whose brother, not politeness towards you. To outsiders: 兄. About the listener's: お兄さん. 私のお兄さん said to a boss sounds like a child speaking; 田中さんの兄 sounds rude. Spanish tú/usted never changes the noun this way.
• Readings shift. 兄 alone is あに, but お兄さん is おにいさん (long い, not おあにさん) and 兄弟 is きょうだい, not きょうてい: this is not rendaku but the go-on reading だい of 弟, just as 妹 reads まい in 姉妹 (しまい). Do not write おにさん: that is 鬼 (おに), a demon.
• Existence takes が + いる. ‘Tengo un hermano’ is 兄がいます (there exists a brother to me), not 兄を持っています. Same for every family member.