Lewis & Short

Sēstos (-us), i, f., = Σηστός, a city in Thrace, on the Hellespont, opposite Abydos, the residence of Hero: Leandri amore pernobilis, Mel. 2, 2, 7; Plin. 4, 11, 18, § 49; Liv. 32, 33; 37, 9; Ov. H. 18, 127; Luc. 2, 674; 6, 55.
Hence,

  1. A. Sēstĭăcus, a, um, adj., of or belonging to Sestos, Sestian: sinus, i.e. the Hellespont, Stat. S. 1, 3, 27: pelagus, Aus. Idyll. 10, 287.
  2. B. Sēstus, a, um, adj., of Sestos, Sestian: puella, i.e. Hero, Ov. H. 17 (18), 2 dub. (the first two lines are probably spurious).
  3. C. Sē-stĭăs, ădis, f., the Sestian, i.e. Hero, Stat. Th. 6, 547; Sid. Carm. 11, 71.