14c. ancle, ankle, from Old English ancleow "ankle," ultimately from PIE root *ang-/*ank- "to bend" (see angle (n.)). The Middle English and modern form of the word seems to be from or influenced by Old Norse ökkla or Old Frisian ankel, which are immediately from the Proto-Germanic form of the root, *ankjōn-(source also of Middle High German anke "joint," German Enke "ankle").
The second element in the Old English, Old Norse and Old Frisian forms perhaps is a folk-etymology suggestion of claw (compare Dutch anklaauw), or it may be from influence of cneow "knee," or it may be the diminutive suffix -el. Middle English writers distinguished inner ankle projection (hel of the ancle) from the outer (utter or utward ancle), and the word sometimes was applied to the wrist (ankle of þe hand).