Lewis & Short

Sperchēos (-ēus) or Sperchīus (-īos, v. Neue, Formenl. 1, 127 sq.), i, m., = Σπερχεῖος, a river of Thessaly, rising on Mount Pindus, now the Ellada; form -eos, Verg. G. 2, 487; Rib., Forb. (al. Sperchius); form -eus, Liv. 36, 14, 15 Weissenb.; 37, 4, 10; form -ios, Mel. 2, 3, 6; Plin. 4, 7, 23, § 28 (v. C. infra), Ov. M. 1, 579; form -ius, Stat. Th. 4, 838.
Hence,

  1. A. Sperchēïs, ĭdis, adj. f., of or belonging to the Spercheos: undae, Ov. M. 7, 230: ripae, id. ib. 2, 250.
  2. B. Sperchīŏnĭdes, ae, m., a dweller by the Spercheos, Ov. M. 5, 86.
  3. C. Sperchiae, ārum f. (Sperchios, Plin. 4, 7, 13, § 28 dub.; Jahn, Sparthos), a town of Thessaly, on the Spercheos, Liv. 32, 13, 10.