Acheron (ACK-uh-ron). One of the rivers of the Underworld. It was at the confluence of the Acheron and the river Styx that the hero Odysseus dug a pit and poured sacrificial blood into it to summon the ghosts of the dead. Odysseus needed to question the shade of the blind prophet Teiresias in order to find his way home again after the Trojan War. Acheron is also the name of a river in modern Greece, still reputed to give access to Hades.