Lewis & Short

Bacchylĭdēs, is, m., = Βακχυλίδης, a Greek lyric poet of Ceos, a nephew of Simonides, who lived about 470 B.C., Amm. 25, 4, 3.
Hence, Bacchylĭdĭus, a, um, adj., of Bacchylides: metrum, Serv. Centim. 2, 5, p. 1819 P.