Infernal /(?)/

In·fer·nal

Infernal

a.
  1. Of or pertaining to or suitable for the lower regions, inhabited, according to the ancients, by the dead; pertaining to Pluto's realm of the dead, the Tartarus of the ancients.
    The Elysian fields, the infernal monarchy.
    — Garth.
  2. Of or pertaining to, resembling, or inhabiting, hell; suitable for hell, or to the character of the inhabitants of hell; hellish; diabolical; as, infernal spirits, or conduct.
    The instruments or abettors in such infernal dealings.

Phrases & Compounds
Infernal machine
a machine or apparatus maliciously designed to explode, and destroy life or property.
Infernal stone
(lapis infernalis), lunar caustic; formerly so called. The name was also applied to caustic potash.

Infernal

n.
  1. An inhabitant of the infernal regions; also, the place itself. [Obs.]