An inferno is a huge fire that's difficult to control, like an inferno that burns down a whole city block. Inferno also can describe any horrible place where people suffer.
The Latin word infernus means "of the lower regions." Using inferno to mean "hell" is credited to medieval Italian poet Dante Alighieri. Dante's epic poem the Divine Comedy contains one part titled The Inferno, which tells of a journey through the nine circles of hell full of torture, pain, and imagery of red — flames, boiling blood, and so on.