夜間

1. Origins, structure, and basic meaning

• Structure: 夜間, read やかん, means the nighttime period rather than one exact moment at night.
• Basic usage: It marks hours when an entrance is locked or modifies a course held at night with 夜間の講座.

2. Common pitfalls and similar expressions

• Nighttime and activities held at night
  • It can mark the period when a gate is locked or modify classes held at night. It describes a nighttime span rather than one exact clock time.