Lewis & Short

Sĭnis, is, m., = Σίνις, a mythical robber on the Isthmus of Corinth, who bound travellers to the tops of pine-trees which he had bent to the ground, and then, by letting go his hold, hurled them into the air; he was killed at last by Theseus, Prop. 3 (4), 22, 37; Ov. M. 7, 440; id. H. 2, 70; Stat. Th. 12, 576.