The contemplation of or meditation upon one's navel; navel-gazing.
(figuratively) Ratiocination to the point of self-absorption.
1952, William Harold Ingrams, Hong Kong, H. M. Stationery Off., page 22,
… like the Muslims who saw Mecca as the world's navel, the British saw London as the world's capital. Omphaloscepsis has always been one of the world's troubles.