The Collaborative International Dictionary of English v.0.48:

Specular \Spec"u*lar\, a. [L. specularis (cf., from the same
   root, specula a lookout, watchtower): cf. F. sp['e]culaire.
   See Speculum.]
   1. Having the qualities of a speculum, or mirror; having a
      smooth, reflecting surface; as, a specular metal; a
      specular surface.
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   2. (Med.) Of or pertaining to a speculum; conducted with the
      aid of a speculum; as, a specular examination.
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   3. Assisting sight, as a lens or the like. [Obs.]
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            Thy specular orb
            Apply to well-dissected kernels; lo!
            In each observe the slender threads
            Of first-beginning trees.             --J. Philips.
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   4. Affording view. [R.] "Look once more, ere we leave this
      specular mount." --Milton.
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   Specular iron. (Min.) See Hematite.
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WordNet (r) 3.0 (2006):

specular
    adj 1: capable of reflecting light like a mirror; "mirrorlike
           surface of the lake"; "a specular metal" [syn:
           mirrorlike, specular]