謎

1. Origins, structure, and basic meaning

• Structure: 謎 is read as なぞ and is a noun for a riddle to be solved or a mystery whose cause or reason remains unknown.
• Basic usage: Use 謎を解く for solving one and 謎のままだ for its remaining unresolved.

2. Common pitfalls and similar expressions

• Riddle and mystery
  • It can be a puzzle involving a room with no key or an unanswered question such as why birds have not returned.
• Continuing state
  • 謎のまま means that the answer remains unknown; it does not mean that there is no question.