お兄さん

1. Origins, structure, and basic meaning

• Structure: お兄さん is read as おにいさん and is a person noun built from 兄 with polite お and the address suffix さん.
• Basic usage: It can mean an older brother or serve as a friendly way to refer to a nearby young man outside the family.

2. Common pitfalls and similar expressions

• Non-relative address
  • 近くのお兄さん is a nearby young man asked for directions, not the speaker’s own brother.
• Family relation
  • In お兄さんは妹に, the word refers to an older brother reading to his younger sister; the relationship context distinguishes the sense.