umbilicus
Concise Oxford English Dictionary © 2008 Oxford University Press:
umbilicus /ʌmˈbɪlɪkəs, ˌʌmbɪˈlʌɪkəs/
▶noun (pl. umbilici /-sʌɪ/ or umbilicuses)
- 1 Anatomy the navel.
- 2 Zoology a central depression or hole in the whorl of some gastropod molluscs and many ammonites.
- 3 Zoology a hole at each end of the hollow shaft of a feather.
'umbilicus' also found in these Oxford entries:

