omphalos

n. navel, umbilicus (Anatomy); center; focal point; ancient Greek round stone in the temple of Apollo at Delphi believed to mark the middle of the earth

An omphalos is an ancient religious stone artifact, or baetylus. In Greek, the word omphalos means "navel" (compare the name of Queen Omphale). According to the ancient Greeks, Zeus sent out two eagles to fly across the world to meet at its center, the "navel" of the world. Omphalos stones used to denote this point were erected in several areas surrounding the Mediterranean Sea; the most famous of those was at the oracle in Delphi.
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Noun
1. scar where the umbilical cord was attached
(synonym) navel, umbilicus, bellybutton, omphalus
(hypernym) point
(part-holonym) abdomen, venter, stomach, belly

(n.)
The navel.
  

[Greek] Omphalos (literally, "navel") is a sacred oval or hemispherical stone in Delphi. There it was situated in the center of the temple of Apollo (currently a museum). To the ancient Greeks this stone was the center, the 'navel', of the earth. According to legend, Zeus determined the spot by sending forth two eagles simultaneously to fly from the eastern and western ends of the earth, and they met at Delphi.