Lewis & Short

Sīthŏnĭi, ōrum, m., = Σιθόνιοι, a Thracian people; hence, poet., in gen., the Thracians, Plin. 4, 11, 18, § 41; Hor. C. 1, 18. 9.
Hence,

  1. A. Sīthŏnĭus, a, um, adj., Sithonian, Thracian: agri, Ov. M. 13, 571: nives, Verg. E. 10, 66; Hor. C. 3, 26, 10: Aquilo, Ov. H. 11, 13: nurus, id. M. 6, 588: rex, id. P. 4, 7, 25.
  2. B. Sīthon, ŏnis, adj., Sithonian, Thracian: Sithones et Scythici triumphi, Ov. F. 3, 719.
  3. C. Sī-thŏnis, ĭdis, adj. f., Sithonian, Thracian: unda, Ov. H. 2, 6.
    Subst., a Thracian woman, Ov. R. Am. 605.