Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
†† ūrus, i, m. [Celtic], a kind of wild ox, a ure-ox, urus, Caes. B. G. 6, 28; Plin. 8, 15, 15, § 38; Verg. G. 2, 374; 3, 532; cf. Macr. S. 6, 4 fin.