Lewis & Short

ornus, i, f.,

  1. I. the wild mountain-ash: steriles orni, Verg. G. 2, 111; Hor. C. 3, 27, 58; Plin. 16, 18, 30, § 73; Col. Arbor. 16; Juv. 1, 11.
  2. II. Transf., a lance made of the wood of this tree: vibrabilis ornus Achilli, Aus. Ep. 24, 108.