Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Aufēius, a, um, adj., of or belonging to the gens Aufeia: aqua, Plin. 31, 3, 24, § 41: lex (A. U. C. 630), named after a tribune of the people, Aufeius, Gell. 11, 10; cf. Meyer, Orat. Fragm. p. 121.