書簡

1. Origins, structure, and basic meaning

• Structure: 書簡(しょかん) is a formal noun for a letter or correspondence.
• Basic usage: It fits contexts such as exhibiting an author's letters or reading old letters as documents.

2. Common pitfalls and similar expressions

• The everyday term 手紙
  • 手紙(てがみ) is the everyday word for a letter.
  • 書簡 often appears when letters are treated as documents, such as in exhibitions, research, or discussion of written records.