Infernal, chthonian, hellish, Hadean, Tartarean, stygian mean of or characteristic of the abode of the dead.
Infernal basically denotes of or characteristic of the underworld regions once held to be inhabited by the earth gods and spirits of the dead. Through confusion of pagan conceptions of the underworld with Jewish and Christian conceptions of hell as the abode of devils and a place of torment for the souls of the damned infernal has acquired connotations of horror, torturing fiends, and unendurable suffering through fire, which nearly always blur and sometimes blot out its original subterranean implications.
When the classical conception of the underworld must be suggested without an admixture of alien connotations, chthonian is sometimes used.
Hellish comes close to the current meaning of infernal but carries so strong an implication of devilishness that it more nearly approaches fiendish in its meaning. Hadean, Tartarean, and stygian are used in poetry in place of infernal, sometimes without any reference to the conception of Hades, Tartarus, and the Styx in classic mythology.
Very frequently Hadean is a loose equivalent for chthonian, Tartarean suggests darkness and remoteness, stygian connotes bounds with no outlet for escape, but all three are without fixed content.