Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Ătū̆rus (on account of the length of the u, sometimes written Aturrus; cf. Arabia; once ŭ, Luc. 1, 420), i, m., = Ἀτούριος, a river in Aquitania, now Adour, Aus. Parent. 4, 11; id. Mos. 468; cf. Mann. Gall. p. 116.