ὀμφαλός .ὀμφᾰλός, οῦ, ὁ, the navel, Lat. umbilicus, Il., Hdt., etc. anything central (like a navel): the knob or boss in the middle of the shield, Lat. umbo, Il. a button or knob on the horseʼs yoke to fasten the reins to, Il. in pl. the knobs at each end of the stick round which books were rolled, Lat. umbilici, Luc. the centre or middle point, as the island of Calypso is the ὀμφαλός of the sea, Od.; and Delphi (or rather a round stone in the Delphic temple) was called ὀμφαλός as marking the middle point of Earth, Pind., Aesch., etc.