Lewis & Short

Ismēnus or -ŏs, i, m., = Ἰσμηνός,

  1. I. a river of Bœotia, near Thebes, Plin. 4, 7, 12, § 25; Ov. M. 2, 244; Stat. Th. 1, 40; 9, 404.
  2. II. Derivv.
    1. A. Ismēnĭus, a, um, adj., = Ἰσμήνιος, of or belonging to Ismenus, Ismenian, poet. for Theban, Ov. M. 13, 682: heros, i. e. Polynices, Stat. Th. 2, 307.
    2. B. Ismēnis, ĭdis, f., = Ἰσμηνίς, a Theban woman, Ov. M. 3, 169; 733; 4, 31.