noun
Standard body-part term; no special register or usage restrictions.
昨日、足首をひねってしまった。
I twisted my ankle yesterday.
彼女は細い足首をしている。
She has slender ankles.
Standard kanji spelling; high-frequency word.
Rarely used kanji form; 頸 is an older character for 'neck' or 'ankle'.
Compound of 足 (あし, 'foot') and 首 (くび, 'neck'), literally 'foot neck'.