Lewis & Short

Amphīon, ŏnis, m., = Ἀμφίων, son of Antiope by Jupiter, king of Thebes, and husband of Niobe; renowned for his music. by the magical power of which the stones came together for the building of the walls of Thebes, Hyg. Fab. 6 and 7; Hor. A. P. 394. He killed himself on account of grief for the loss of his children, who had been slain by the arrows of Apollo and Diana, Ov. M. 6, 221; 6, 271; 6, 402: Amphionis arces, i. e. Thebes, id. ib. 15, 427.
Whence, Amphīŏnĭus, a, um, adj., Amphionian: Amphioniae lyrae, Prop. 1, 9, 10.