Lewis & Short

spīnōsus, a, um, adj. [spina], full of thorns or prickles, thorny, prickly.

  1. I. Lit.: caprae in spinosis locis pascuntur, Varr. R. R. 2, 3, 8: herbae, Ov. M. 2, 810: frutecta, Plin. 30, 11, 30, § 101: caulis, id. 19, 3, 17, § 47: folia, id. 20, 23, 99, § 262: cortex, id. 12, 15, 34, § 67: spinosior arbor, id. 24, 12, 67, § 109: fragmenta vertebrae, Cels. 8, 9 fin.
  2. II. Trop., thorny.
      1. 1. Of style, harsh, crabbed, obscure, confused, perplexed: Stoicorum spinosum disserendi genus, Cic. Fin. 3, 1, 3: oratio, id. de Or. 1, 18, 83.
        Comp.: haec enim spinosiora prius ut confitear me cogunt, Cic. Tusc. 1, 8, 16; id. Or. 32, 114; Varr. L. L. 8, § 51 Müll.
        Sup.: praeceptorum nodosissimae et spinosissimae disciplinae, Aug. Doctr. Chr. 2, 37.
      2. 2. Of cares, stinging, galling. irritating: curae, Cat. 64, 72; cf. spina, II.