Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Ărĭūsĭus, a, um, adj.: vina, wine of the region of Ariusia, in the island Chios (Ἀριουσία χώρα, Strabo), Verg. E. 5, 71: pocula, Sil. 7, 210.