Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Xerxes (Xerses, Cic. Leg. 2, 10, 26), is (i, Nep. Reg. 1), m., = Ξέρξης, the celebrated king of Persia, son of Darius Hystaspis, vanquished by the Greeks at Salamis, Cic. Tusc. 5, 7, 20; id. N. D. 1, 41, 115.