Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. pā̆trŭus, i, m. [pater, like the Sanscr. pitrivya, patruus, from pitri], a father’s brother, paternal uncle (opp. avunculus, a mother’s brother, maternal uncle); cf. Dig. 38, 10, 10.
2. pătrŭus, a, um, adj. [1. patruus], of or belonging to a father’s brother, of an uncle (poet.): patruae verbera linguae, an uncle’s, Hor C. 3, 12, 2: ense cadit patruo, Ov. F. 4, 55 (al. patrui).
Comically in sup.: patrue mi patruissime, my uncle, my best of uncles! Plaut. Poen. 5, 4, 24; 26.