Lewis & Short

mūrus (archaic orthogr. moerus, Varr. L. L. 5, 32, § 41 Müll.; Enn. ap. Serv. Verg. G. 1, 18, or Ann. v. 376 Vahl.; Verg. A. 10, 24: moirus, Inscr. Orell. 566), i, m. [from root mū-; cf.: moenia, munis], a wall; esp. a city wall; mostly in plur. (class.; cf.: moenia, paries, maceria).

  1. I. Lit.: muri urbis, Cic. N. D. 3, 40, 94: Helvii intra oppida murosque compelluntur, Caes. B. G. 7, 65: instruere, Nep. Th. 6, 4: ducere, Verg. A. 1, 423: aedificare, Ov. M. 11, 204: marmoreus, a balcony, Calp. Ecl. 7, 48.
    Also, the wall of a building, Cic. Att. 2, 4, 7: sanctae res, veluti muri et portae, quodammodo divini juris sunt, Gai. Inst. 2, 9.
    1. B. Transf.
      1. 1. A bank, mound, dam, Varr. R. R. 1, 14, 3.
      2. 2. The rim or side of a pot or boiler: quae tenui muro spatiosum colligat orbem, Juv. 4, 132.
      3. 3. The wooden tower of an elephant, Sil. 9, 601.
      4. 4. The head-dress of Cybele, ornamented with towers: crinalis, Claud. in. Eutr. 2, 284.
  2. II. Trop., a wall, a safeguard, protection, defence (rare but class.): lex Aelia et Fufia, propugnacula murique tranquillitatis, Cic. Pis. 4, 9: Graiūm murus Achilles, Ov. M. 13, 280: cor munitum costarum et pectoris muro, Plin. 11, 37, 69, § 181: hic murus aëneus esto, Hor. Ep. 1, 1, 60.