Avernian, a-ver'-ne-an,

Nuttall's Standard Dictionary of the English Language · 1890 · p. 13

a. pertaining to the lake Avernus, in Italy, famous for its poisonous exhalations, and fabled by the ancients to be the entrance to the infernal regions. formerly paid towards conveying the king's carriages [Old Law]. (L. a, and verrunco, turn)