malleolus

noun

mal·​le·​o·​lus mə-ˈlē-ə-ləs 

plural malleoli -ˌlī 

: an expanded projection or process at the distal end of the fibula or tibia at the level of the ankle:

a

: the expanded lower end of the fibula situated on the lateral side of the leg at the ankle

called also external malleolus, lateral malleolus

b

: a strong pyramid-shaped process of the tibia that projects distally on the medial side of its lower end at the ankle

called also internal malleolus, medial malleolus

c

: a small projection of the tibia on the posterior side of its lower end at the ankle

called also posterior malleolus