dawn

1. Origins, structure, and basic meaning

• Structure: 旦 has 5 strokes; 一旦 is read いったん, and 元旦 is read がんたん.
• Basic usage: 一旦 means for the time being or once a condition has been met; 元旦 denotes the first morning of the new year.

2. Common pitfalls and similar expressions

• A temporary stop and a condition once met
  • 作業を一旦中止した means stopping work for the time being. It describes the immediate decision without specifying when work will resume.
  • 一旦出ると introduces the condition once you leave. Rendering this use of 一旦 as merely leaving briefly would miss its connection to the subsequent restriction on reentry.