Lewis & Short

spĕcŭlum, i, n. [specio; hence, that in which one sees himself].

  1. I. Lit., a looking-glass, mirror (usually made of polished metal): speculum a speciendo, quod ibi se spectant, Varr. L. L. 5, § 129 Müll.; cf.: speculum, quod in eo specimus imaginem, id. ib. 6, § 82: homines sibi habere speculum, ubi os contemplarent suom, etc., Plaut. Ep. 3, 3, 2: quid opu’st speculo tibi, quae tute speculo speculum es maximum? id. Most. 1, 3, 94; cf. id. Men. 5, 9, 3: speculi imago, Lucr. 4, 279; cf. id. 4, 331: speculis apparent simulacra, id. 4, 98: speculorum levitas, Cic. Univ. 14: quotiens te in speculo videris alterum, Hor. C. 4, 10, 6: ut in speculo rugas aspexit aniles, Ov. M. 15, 232: se in speculo contemplari, App. Mag. p. 283, 4: cava specula, id. ib. p. 284, 2 et saep.
    On the material and use of mirrors, v. Plin. 33, 9, 45, § 128; 34, 17, 48, § 160; 37, 5, 16, § 64; 37, 7, 25, § 97; Stat. S. 3, 4, 94; Sen. Q. N. 1, 17.
    With tanquam, ut, etc.: inspicere, tamquam in speculum, in vitas omnium, Ter. Ad. 3, 3, 61; 3, 3, 74; Cic. Pis. 29, 71; id. Fin. 5, 22, 61; id. Rep. 2, 42, 69.
    1. B. Poet., transf., of the mirror-like smoothness of water: lympharum in speculo, Phaedr. 1, 4, 3.
  2. II. Trop., a mirror, copy, imitation (rare; more freq. connected with tamquam or ut, etc.; v. supra, I.): futuri temporis, Lucr. 3, 974; 4, 166: infantes et bestias putat specula esse naturae, Cic. Fin. 2, 10, 32; cf. corresp. with imago, Plaut. Men. 5, 9, 3: omne opus Vergilianum de quodam Homerici operis speculo formatum est, Macr. S. 5, 2 med.