The Collaborative International Dictionary of English v.0.48:

Obscure \Ob*scure"\ ([o^]b*sk[=u]r"), a. [Compar. Obscurer
   ([o^]b*sk[=u]r"[~e]r); superl. Obscurest.] [L. obscurus,
   orig., covered; ob- (see Ob-) + a root probably meaning, to
   cover; cf. L. scutum shield, Skr. sku to cover: cf. F.
   obscur. Cf. Sky.]
   [1913 Webster]
   1. Covered over, shaded, or darkened; destitute of light;
      imperfectly illuminated; dusky; dim.
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            His lamp shall be put out in obscure darkness.
                                                  --Prov. xx.
                                                  20.
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   2. Of or pertaining to darkness or night; inconspicuous to
      the sight; indistinctly seen; hidden; retired; remote from
      observation; unnoticed.
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            The obscure bird
            Clamored the livelong night.          --Shak.
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            The obscure corners of the earth.     --Sir J.
                                                  Davies.
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   3. Not noticeable; humble; mean. "O base and obscure vulgar."
      --Shak. "An obscure person." --Atterbury.
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   4. Not easily understood; not clear or legible; abstruse or
      incomprehensible; as, an obscure passage or inscription.
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   5. Not clear, full, or distinct; clouded; imperfect; as, an
      obscure view of remote objects.
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   Obscure rays (Opt.), those rays which are not luminous or
      visible, and which in the spectrum are beyond the limits
      of the visible portion.
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   Syn: Dark; dim; darksome; dusky; shadowy; misty; abstruse;
        intricate; difficult; mysterious; retired; unnoticed;
        unknown; humble; mean; indistinct.
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The Collaborative International Dictionary of English v.0.48:

Obscurer \Ob*scur"er\ ([o^]b*sk[=u]r"[~e]r), n.
   One who, or that which, obscures.
   [1913 Webster]