umbilicus vs omphalus

umbilicus and omphalus both are nouns.

Word	Noun	Adjective	Verb	Adverb
umbilicus	Yes	No	No	No
omphalus	Yes	No	No	No

As nouns, umbilicus and omphalus are synonyms defined as:

Other synonyms of umbilicus include belly button, bellybutton, navel, omphalos.

umbilicus (noun)	omphalus (noun)
a scar where the umbilical cord was attached	a scar where the umbilical cord was attached