期間

1. Origins, structure, and basic meaning

• Structure: 期間 (きかん) combines term 期 and interval 間 to denote a bounded period of time.
• Basic usage: It covers an application window ending at month-end or the entire time construction is under way.

2. Common pitfalls and similar expressions

• An endpoint and the interval leading to it
  • 期間は月末まで states the closing boundary, while 期間中 refers to the span before that boundary.