Acherusia, A fenne in the realme of Naples. It is also a poole or meere of Thesprotia in Epire, out of which issueth the riuer Acheron, which runneth into the sea called Ambracium. Acherusia, is also an hole or caue, which the Poets suppose to be a way into hell. Out of this hole Hercules drew Cerberus, the dogge of hell. The painims belieued, % all soules went that way into the fennes or meers called Stigiæ paludes, where Charon receined them into his boate.
Lewis and Short: Latin dictionary
Ăchĕrūsĭa, ae, f. [Acheruns]. I. Acherusia Palus, A.A lake in Epirus, through which the Acheron flows, Plin. 4, 1, 1.—B.A lake in Campania, between Misenum and Cumae, now Lago di Fusaro, Plin. 3, 5, 9.—II.A cave in Bithynia, from which Cerberus is said to have been dragged, Mel. 1, 19, 7; Plin. 6, 1, 1; the same called Ăchĕrūsĭs, ĭdis, f., Val. Fl. 5, 73.
Ăchĕrūsĭus (old writing Acherunsius), a, um, adj. [id.]. I.Pertaining to the Acheron in Calabria: aqua, Liv. 8, 24.— II.Pertaining to the Acheruns (Acheron), or the Lower World: templa, the Lower World, Enn. ap. Cic. Tusc. 1, 21, 48 (Trag. v. 107 ed. Vahl.); in Varr. L. L. 7, 6 Müll.; and in Lucr. 1, 120; cf. Lucr. 3, 25 and 86: humor, Sil. 13, 398: vita,
a life of gloom
, Lucr. 3, 1024.—III.Pertaining to Acheron in Epirus: amnis, Just. 12, 2, 3.