Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun underworld

2 senses of underworld

Sense 1
underworld -- (the criminal class)
       => class, stratum, social class, socio-economic class -- (people having the same social, economic, or educational status; "the working class"; "an emerging professional class")

Sense 2
Hell, Hades, infernal region, netherworld, Scheol, underworld -- ((religion) the world of the dead; "No one goes to Hades with all his immense wealth"-Theognis)
       => imaginary place, mythical place, fictitious place -- (a place that exists only in imagination; a place said to exist in fictional or religious writings)