Lewis & Short

ōbex, obĭcis (objĭcis), m. and f. (of either gender indifferently; very rare in nom. sing.; acc. not found, v. Neue, Formenl. 1, p. 489) [obicio, that which is cast or placed before; hence], a bolt, bar; a barrier, wall (mostly poet. and in post-Aug. prose; not in Cic. or Cæs.).

  1. I. Lit.: obices pessuli, serae, Paul. ex Fest. p. 187 Müll.: fultosque emuniit obice postes, Verg. A. 8, 227; cf. Ov. M. 14, 780: ferrati portarum obices, Tac. H. 3, 30: obices portarum subversi, id. A. 13, 39; Sil. 4, 24: diffractis portarum obicibus, Amm. 24, 5: infirmā scamellorum obice fultae fores, App. ap. Prisc. p. 615 P.: saxi, Verg. G. 4, 422: ecce maris magnā claudit nos obice pontus, id. A. 10, 377: quā vi maria alta tumescant Obicibus ruptis, their barriers, i. e. their rocky shores, id. G. 2, 480; Gell. 17, 11 fin.
  2. II. Transf., a hinderance, impediment, obstacle: apud hanc obicem, Plaut. Pers. 2, 2, 21: per obices viarum, Liv. 9, 3, 1; 2, 58; 6, 33, 11: nullae obices, nulli contumeliarum gradus, obstacles to admission, Plin. Pan. 47, 5; Inscr. Orell. 708.