Ashikubi 足首
Japanese for ankle; ashikubi is the anatomy word riggers use for the ankle, met in tie names such as ashikubi futomomo shibari, a bent-leg tie.
Ashikubi (足首) is the common Japanese word for ankle, built from ashi, leg or foot, and kubi, neck; Jisho also lists the rare spelling 足頸. Shibari Study includes it in its anatomy vocabulary and in the name ashikubi futomomo shibari, a tie that holds the leg bent. Shibari Study notes that the word is most often met in that full name, the ankle being where the rope joins the leg to the thigh.