Cocytus

Cocytus, meaning "the river of wailing" (from the Greek κωκυτός, "lamentation"), is a river in the underworld in Greek mythology. The recently deceased who could not pay Charon to ferry them across this river were condemned to wander its banks for one hundred years (according to most accounts). Cocytus flowed into the river Acheron, across which dwelled Hades, the mythological abode of the dead.
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Noun
1. (Greek mythology) a river in Hades that was said to be a tributary of the Acheron
(synonym) River Cocytus
(hypernym) river
(part-holonym) Hel, Hell, Hades, infernal region, netherworld, Scheol, underworld
(classification) Greek mythology

[Greek] One of the five rivers of Hades, which flows into the Acheron. The name means "river of lamentation." The unburied were doomed to wander about its banks for hundred years.