Properly, pertaining to the lower regions, or regions of the dead, the Tartarus of the ancients. Hence,

Pertaining to hell; inhabiting hell; as infernal spirits.

Hellish; resembling the temper of infernal spirits; malicious; diabolical; very wicked and detestable.

An inhabitant of hell, or of the lower regions. Infernal stone a name formerly given to lunar caustic, a substance prepared from an evaporated solution of silver, or from crystals of silver. Lunar caustic is nitrate of silver fused and cast in small cylinders.