Lewis & Short

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.