malleolus
Concise Oxford English Dictionary © 2008 Oxford University Press:
malleolus /maˈliːələs/
▶noun (pl. malleoli /-lʌɪ/) Anatomy a bony projection with a shape likened to a hammer head, especially each of those on either side of the ankle.
– origin C17: from L., dimin. of malleus ‘hammer’.
'malleolus' also found in these Oxford entries:

