糸口

1. Origins, structure, and basic meaning

• Structure: 糸口 is read as いとぐち and means “clue” and “lead”.
• Basic usage: It denotes an old photo becoming a clue and searching for an opening to resume talks.

2. Common pitfalls and similar expressions

• 調査の糸口になる / 再開する糸口を探す
  • Use 調査の糸口になる for an identified clue and 再開する糸口を探す for an opening still sought.