What is another word for "umbilicus"?

Roget's Thesaurus (1911) lists these synonyms for "umbilicus": axial, axis, azygous, backbone, bring, buoyancy, center, central, centrality, centralization, centralize, centrally, centrical, column, concentrate, concentration, concentric, converge, convergence, core, eye, focal, focus, gravity, heart, hotbed, kernel, marrow, metacenter, middle, middlemost, midst, nave, navel, nucleolus, nucleus, oscillation, percussion, pith, pole.