WordNet (r) 3.0 (2006):

omphalus
    n 1: a scar where the umbilical cord was attached; "you were not
         supposed to show your navel on television"; "they argued
         whether or not Adam had a navel"; "she had a tattoo just
         above her bellybutton" [syn: navel, umbilicus,
         bellybutton, belly button, omphalos, omphalus]