Lewis Short
būris | būra, ae (noun M.f) : m. (, , f., Varr. R. R. 1, 19, 2) [acc. to Serv. ad Verg. G. 1, 170 (cf. also Isid. Orig. 20, 14, 2), contr. from βοῦς and οὐρά, ox-tail]
* The curved hinder part of the plough of the ancients, the plough-beam, Varr. ap. Serv. l. l.—Acc. burim, Verg. G. 1, 170 Serv. and Voss.; Varr. R. R. 1, 19, 2.
Charlton T. Lewis, Charles Short, A Latin Dictionary