promise · approximately

1. Origins, structure, and basic meaning

• Structure: 約 has 9 strokes and appears in words for making promises or condensing information.
• Basic usage: 約束 is read やくそく, and 要約 is read ようやく.

2. Common pitfalls and similar expressions

• The content of a promise
  • 一緒に遊ぶ約束をした means promised to play together.
  • The action before 約束 specifies what was promised.
• What is summarized and to what length
  • 長い説明を三行に要約して means summarizing a long explanation in three lines.
  • With 要約する, を marks the material summarized and に marks the resulting length.