Lewis & Short

Pēlĭon, ii (masc. collat. form Pēlĭos, Plin. 4, 8, 15, § 30: Pelio, scanned as a dissyl. per syniz., Sil. 3, 495), n., = Πήλιον, a high mountain in Thessaly, a continuation of Ossa, now Zagora, Plin. 2, 65, 65, § 162; Verg. G. 1, 281; 3, 94; Ov. M. 12, 513; 1, 155; Mel. 2, 3, 2.
Hence,

  1. A. Pēlĭăcus, a, um, adj., of or belonging to Pelion: vertex, Cat. 64, 1: apex, Ov. F. 1, 308: juga, Stat. Achill. 1, 321: trabs, i.e. the Argo (because built of timber from Pelion), Prop. 3 (4), 22, 12: Peliaca carina, Val. Fl. 8, 417; cf. also: Peliaca cuspis, of Achilles, cut on Pelion, Ov. M. 12, 74: axis, the chariot of Achilles, Sen. Troad. 414.
  2. B. Pēlĭus, a, um, adj., of or belonging to Pelion, Pelian: mons, Cic. Fat. 15, 35: in nemore Pelio, Enn. ap. Auct. ad Her. 2, 22, 34 (Trag. v. 280 Vahl.); so, in imitation, nemus, Phaedr. 4, 7, 6.
  3. C. Pēlĭas, ădis, f. adj., that comes from Pelion: Pelias hasta, the spear of Achilles (because its shaft came from Pelion), Ov. H. 3, 126: pinus, the Argo, Stat. Th. 5, 335.
    As subst.: Pēlĭas, ădis, f., a spear, Auct. Pan. ad Pis. 165.