Lewis & Short

nūbĭgĕna, ae, comm. [nubes-gigno], cloud-born, born of clouds or of a cloud (poet.).

  1. I. In gen.: amnes, Stat. Th. 1, 365: nimbi, Prud. Hamart. 486: clipei, the Ancilia (so called because they fell from the sky), Stat. S. 5, 2, 131.
  2. II. In partic.
    1. A. The Centaurs, whom Ixion begot of a cloud, Stat. Th. 5, 263; Ov. M. 12, 211; 541; cf. Hyg. Fab. 62.
    2. B. Phrixus, as the son of Nephele: Phrixus nubigena, Col. poët. 10, 115.