足首

The term refers specifically to the joint area between the leg and the foot. In Japanese, the word "ashi" (足) can refer to both the entire leg and the foot, but "ashikubi" (足首) precisely isolates the ankle area.

In daily conversation, it is most frequently used in the context of injuries, such as sprains or fractures, or when describing the length of clothing and footwear (e.g., ankle-length boots or socks).

While it is a neutral anatomical term, it is used across all registers, from casual conversation to medical reports. There are no significant politeness variations for this word, as it is a standard noun for a body part.