Noun
A projection at the distal end of each bone of the leg at the ankle joint. The malleolus of the tibia is the internal projection, that of the fibula the external.
" A layer, " a shoot partly buried in the ground, and there cut halfway through.
Source: Webster's dictionaryDorsiflexion (extension) and plantar flexion occur around the transverse axis running through the ankle joint from the tip of the medial malleolus to the tip of the lateral malleolus. Source: Internet