underworldPronunciation: /ˈʌndəwəːld/Translate underworld | into French | into German | into Italian | into Spanish Definition of underworld noun 1the world of criminals or of organized crime: a man reputed to be a godfather of the Glasgow underworld [as modifier]:a prominent underworld figure 2the mythical abode of the dead, imagined as being under the earth. underworld in other Oxford dictionaries Definition of underworld in the US English dictionary