A central point, a hub or focal point, or the center of activity. "Omphalos" originally meant navel or umbilicus (bellybutton) in ancient Greece. When placed as a boss at the center of a vessel or of a shield, an omphalos symbolized the center of the world. The ancients also used it to designate a circular altar at Delphi, which was considered the center of the earth.(pr. AHM-fə-l?s)"Omphaloskepsis" is a practice that appeared among English speakers in the 1920s, and means "contemplation of one's navel."