In-fĕr'nal1, a.
a. [Lat. infernalis, from infernus, that which lies beneath, the lower; It. infernale, Fr., Pr., Sp., & Pg., infernal.]
Sense 1. Pertaining to the lower regions, or regions of the dead, the Tartarus of the ancients. “The Elysian fields, the infernal monarchy.” Garth.
Sense 2. Pertaining to hell; resembling hell; inhabiting hell; suitable to the character of the inhabitants of hell; hellish; diabolical; as, infernal spirits, or conduct.
Infernal machine, a machine or apparatus contrived so as to explode unexpectedly or under certain conditions, for the purpose of assassination or other mischief. — Infernal stone (lapis infernalis), lunar caustic; — formerly so called. The name was also applied to caustic potash.
Synonyms— Tartarean; Stygian; hellish; devilish; diabolical; satanic; fiendish; malicious.