The term "underworlds" is often used to refer to the realm of the dead or the criminal underworld. However, there are numerous synonyms that can be used to describe these realms. Some examples of synonyms for the term "underworlds" include the netherworld, the abyss, the inferno, the depths, the subterranean, the depths of hell, the criminal underworld, the seedy underbelly of society, the criminal abyss, the dark underbelly of society, or the shadowy realm of criminals. Each of these synonyms can be used to describe various aspects of the underworld, from the mythical realm of the dead to the grimy and dangerous world of organized crime.