Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Ăchĕruns, untis, m. [v. Acheron] (f., Plaut. Capt. 5, 4, 2; cf. Non. 191, 24; poet. in Cic. Tusc. 1, 16, 37; the u for o, as in Enn. and Lucr. frundes for frondes, acc. Gr. Acherunta, Lucr. 4, 170; 6, 251); a form much used by ante-class. poets, esp. by Plaut.,
- I. For Acheron no. II. B.: adsum atque advenio Acherunte, poet. ap. Cic. Tusc. 1, 16, 37; Rib. Trag. Rel. p. 245; si ab Acherunte veniam, Plaut. Am. 5, 1, 26; so Lucr. 3, 37; 628 al.
And with the ending i (as in Karthagini): si neque hic neque Acherunti sum, ubi sum? Plaut. Merc. 3, 4, 21; so id. Capt. 3, 5, 31; 5, 4, 1.
Acheruntis pabulum, food for Acheron; said of a corrupt, abandoned man, in Plaut. Cas. 2, 1, 12: Acheruntis ostium, disparagingly of bad land, id. Trin. 2, 4, 124: mittere aliquem Acheruntem, to kill one, id. Cas. 2, 8, 12; and: abire ad Acheruntem, to die, id. Poen. prol. 71: ulmorum Acheruns, jestingly of a slave, upon whose back rods had been broken, id. Am. 4, 2, 9 (cf. Capt. 3, 4, 117).
Hence, Ăchĕruntĭcus, a, um, adj., belonging to, or fit for, Acheruns, or the Lower World: regiones, Plaut. Bacch. 2, 2, 21: senex, i. e. with one foot in the grave, id. Merc. 2, 2, 19; id. Mil. 3, 1, 33.