The Collaborative International Dictionary of English v.0.48:

obscurity \ob*scu"ri*ty\ ([o^]b*sk[=u]"r[i^]*t[y^]), n. [L.
   obscuritas: cf. F. obscurit['e].]
   The quality or state of being obscure.

   Syn: darkness; privacy; inconspicuousness;
        unintelligibleness; uncertainty.
        [1913 Webster]

              You are not for obscurity designed. --Dryden.
        [1913 Webster]

              They were now brought forth from obscurity, to be
              contemplated by artists with admiration and
              despair.                            --Macaulay.
        [1913 Webster]

   Syn: Darkness; dimness; gloom. See Darkness.
        [1913 Webster]

WordNet (r) 3.0 (2006):

obscurity
    n 1: the quality of being unclear or abstruse and hard to
         understand [syn: obscureness, obscurity,
         abstruseness, reconditeness] [ant: clarity,
         clearness, limpidity, lucidity, lucidness,
         pellucidity]
    2: an obscure and unimportant standing; not well known; "he
       worked in obscurity for many years" [ant: prominence]
    3: the state of being indistinct or indefinite for lack of
       adequate illumination [syn: obscurity, obscureness]

Moby Thesaurus II by Grady Ward, 1.0:

149 Moby Thesaurus words for "obscurity":
   Egyptian darkness, Erebus, a nobody, a nothing, abstruseness,
   adiaphanousness, ambiguousness, amorphia, amorphism, amorphousness,
   anarchy, anonymity, arcanum, blackness, bleariness, blobbiness,
   blur, blurriness, broadness, chaos, cipher, cloudiness, common man,
   complexity, confusion, dark, darkness, darkness visible,
   dead of night, defocus, dimness, disorder, dummy, dusk, duskiness,
   entropy, esoterica, faintness, feebleness, figurehead, filminess,
   fog, fogginess, formlessness, fuzziness, generality, gloom,
   half-visibility, haze, haziness, ill-definedness,
   imperviousness to light, imprecision, inaccuracy, inchoateness,
   incoherence, indecisiveness, indefinableness, indefiniteness,
   indeterminateness, indistinctness, indistinguishability,
   inexactness, ingloriousness, insignificance, insignificancy,
   intense darkness, intransparency, intricacy, jackstraw, laxity,
   lightlessness, lightweight, limbo, little fellow, little guy,
   looseness, low profile, man of straw, mediocrity, messiness, mist,
   mistiness, moonlessness, mumbo jumbo, murk, murkiness, mystery,
   mystification, namelessness, nebbish, nebulousness, night,
   nobody one knows, nonentity, obfuscation, obscurantism,
   obscuration, obscure, obscure darkness, opacity, opaque,
   opaqueness, orderlessness, paleness, perplexity, pip-squeak,
   pitch-darkness, pitchy darkness, punk, roil, roiledness, runt,
   scrub, secret, semivisibility, shade, shadow, shadowiness,
   shapelessness, shrimp, small fry, small potato, small potatoes,
   soft focus, squirt, squit, starlessness, sunlessness, swarthiness,
   sweepingness, tenebrosity, tenebrousness, the palpable obscure,
   total darkness, turbidity, turbidness, uncertainty, unclarity,
   unclearness, unimportance, unintelligibility, unplainness,
   vague appearance, vagueness, velvet darkness, weakness, whiffet,
   whippersnapper