Lewis & Short

Cythnŏs or -us, i, f., = Κύθνος,

  1. I. one of the Cyclades, now Thermia, Mel. 2, 7, 11; Plin. 4, 12, 22, § 66; Liv. 31, 15, 8; Ov. M. 5, 252; Tac. A. 3, 69; id. H. 2, 8.
    Hence,
  2. II. Cythnius, a, um, adj., of Cythnos, Cythnian: Timanthes Cythnos, Quint. 2, 13, 13.