The Collaborative International Dictionary of English v.0.48:

Ankle \An"kle\ ([a^][ng]"k'l), n. [OE. ancle, anclow, AS.
   ancleow; akin to Icel. ["o]kkla, ["o]kli, Dan. and Sw. ankel,
   D. enklaauw, enkel, G. enkel, and perh. OHG. encha, ancha
   thigh, shin: cf. Skr. anga limb, anguri finger. Cf.
   Haunch.]
   The joint which connects the foot with the leg; the tarsus.
   [1913 Webster]

   Ankle bone, the bone of the ankle; the astragalus.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ankle
    n 1: a gliding joint between the distal ends of the tibia and
         fibula and the proximal end of the talus [syn: ankle,
         ankle joint, mortise joint, articulatio talocruralis]