正門

1. Origins, structure, and basic meaning

• Structure: 正門 is read as せいもん and refers to the main gate of a school or facility.
• Basic usage: It can be a destination where people gather or an entrance contrasted with another gate when access changes.

2. Common pitfalls and similar expressions

• A destination
  • In 正門へ集まる, the main gate is the place toward which people gather. Example: 生徒たちは朝八時に正門へ集まった。
• Contrast with another gate
  • 正門ではなく東門 explicitly contrasts not using the main gate with using the east gate. Example: 工事中なので正門ではなく東門を使う。