Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Silŭres, um, m., = Σίλυρες, a warlike people of Britain, Plin. 4, 16, 30, § 103; Tac. A. 12, 32; id. Agr. 11 and 17; cf. Mannert, Britan. p. 53 sq.