Jastrow: שָׁרָר

שָׁרָר m. (b. h. שֹׁר , with suffix שָׁרְר׳; שרר to knot, chain) navel, umbilical cord. Num. R. s. 14 (ref. to Cant. VII, 3) והיא משולה בש׳ and it (the Sanhedrin) is compared to the navel; מה הש׳ הזה וכ׳ as the navel is placed in the centre of the body, so are the Sanhedrin &c.; Tanḥ. Ki Thissa 2 (in parallels טיבור). Ib. מה הש׳ הזה … ומן הש׳ הוא אוכל וכ׳ as with regard to the umbilical cord, so long as the child is in its mother’s womb, its mouth is closed, and it is fed from the umbilical cord, so &c. Tanḥ. Thazr. 5 שׁוֹרְרוֹ יוצא עמו וכ׳ its navel comes out with it (the infant) …, and the mother has to cut it off.