Jamieson, Fausset & Brown, on Jer 51:41

“How is Sesach taken, and the renowned one of all the earth surprised? How is Babylon become an astonishment among the nations?”

“Sheshach--Babylon (compare Note, see Jer 25:26); called so from the goddess Shach, to whom a five days' festival was kept, during which, as in the Roman Saturnalia, the most unbridled licentiousness was permitted; slaves ruled their masters, and in every house one called Zogan, arrayed in a royal garment, was chosen to rule all the rest. He calls Babylon "Sheshach," to imply that it was during this feast the city was taken [SCALIGER].”

Imported from an open dataset — not yet checked against the printed edition.