Lewis Short
(adjective) : quinquāgēsĭmus, a, um, [quinquaginta].
* The fiftieth: anno trecentesimo et quinquagesimo fere post Romam conditam,Cic. Rep. 1, 16, 25; 2, 35, 60: quinquagesimo uno raptus anno,Plin. 7, 8, 6, § 46: liba,Mart. 10, 24, 4.
* Subst.: quinquāgēsĭma, ae, f. (sc. pars), a fiftieth part, a fiftieth, as a tax: ab omnibus enim ternae praeterea quinquagesimae exigebantur,Cic. Verr. 2, 3, 49, § 116: binae,id. ib. 2, 3, 78, § 181.
Charlton T. Lewis, Charles Short, A Latin Dictionary