Underverse n. : The lower or second verse.

Example:
Did Dick Cheney return to the Underverse that spawned him?

Taxonomy
Riddick, The Chronicles of Riddick, Lord Marshal, Vaako, Kyra, Necromonger, Helion, Necromongers, sequels, Richard B. Riddick, Imam, Toombs, Vin Diesel, death, Director's Cut, Purifier, David Twohy, Jack.

Defination from the web:
... a race of conquerors travelling across space toward the Underverse, a dark mirror of the normal universe where death has ... The epilogue of the novel adaptation goes even further with Riddick ordering the Necromonger fleet to the Threshold, gateway to the Underverse. ...