足首

1. Origins, structure, and basic meaning

• Structure: 足首(あしくび) means the ankle, where the leg and foot meet.
• Basic usage: It is used for ankle injuries or for describing how high water reaches.

2. Common pitfalls and similar expressions

• Compared with the wrist
  • 手首(てくび) means the wrist; 足首 means the ankle.
• A limit in height
  • 足首まで means up to ankle height.
  • まで marks how far the water reaches.