The Collaborative International Dictionary of English v.0.48:

Blur \Blur\ (bl[^u]r), v. t. [imp. & p. p. Blurred (bl[^u]rd);
   p. pr. & vb. n. Blurring.] [Prob. of same origin as blear.
   See Blear.]
   1. To render obscure by making the form or outline of
      confused and uncertain, as by soiling; to smear; to make
      indistinct and confused; as, to blur manuscript by
      handling it while damp; to blur the impression of a
      woodcut by an excess of ink.
      [1913 Webster]

            But time hath nothing blurred those lines of favor
            Which then he wore.                   --Shak.
      [1913 Webster]

   2. To cause imperfection of vision in; to dim; to darken.
      [1913 Webster]

            Her eyes are blurred with the lightning's glare.
                                                  --J. R. Drake.
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   3. To sully; to stain; to blemish, as reputation.
      [1913 Webster]

            Sarcasms may eclipse thine own,
            But can not blur my lost renown.      --Hudibras.
      [1913 Webster]

   Syn: To spot; blot; disfigure; stain; sully.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Blur \Blur\ (bl[^u]r), n.
   1. That which obscures without effacing; a stain; a blot, as
      upon paper or other substance.
      [1913 Webster]

            As for those who cleanse blurs with blotted fingers,
            they make it worse.                   --Fuller.
      [1913 Webster]

   2. A dim, confused appearance; indistinctness of vision; as,
      to see things with a blur; it was all blur.
      [1913 Webster]

   3. A moral stain or blot.
      [1913 Webster]

            Lest she . . . will with her railing set a great
            blur on mine honesty and good name.   --Udall.
      [1913 Webster]

WordNet (r) 3.0 (2006):

blur
    n 1: a hazy or indistinct representation; "it happened so fast
         it was just a blur"; "he tried to clear his head of the
         whisky fuzz" [syn: blur, fuzz]
    v 1: become glassy; lose clear vision; "Her eyes glazed over
         from lack of sleep" [syn: film over, glaze over,
         blur]
    2: to make less distinct or clear; "The haze blurs the hills"
       [ant: focus]
    3: make unclear, indistinct, or blurred; "Her remarks confused
       the debate"; "Their words obnubilate their intentions" [syn:
       confuse, blur, obscure, obnubilate]
    4: make a smudge on; soil by smudging [syn: smear, blur,
       smudge, smutch]
    5: make dim or indistinct; "The fog blurs my vision" [syn:
       blur, blear] [ant: focalise, focalize, focus,
       sharpen]
    6: become vague or indistinct; "The distinction between the two
       theories blurred" [syn: blur, dim, slur] [ant:
       focalise, focalize, focus]

Moby Thesaurus II by Grady Ward, 1.0:

141 Moby Thesaurus words for "blur":
   aspersion, attaint, badge of infamy, bar sinister, baton, becloud,
   bedaub, bedim, befog, bend sinister, besmear, besmirch, besmoke,
   bestain, black eye, black mark, blacken, blear, bleariness,
   bloodstain, blot, blotch, blur distinctions, blurriness, brand,
   broad arrow, censure, champain, cloud, cloudiness, conceal,
   confound, confuse, dab, darken, darkness, daub, defocus, deform,
   dim, dimness, dirty, discolor, disorder, disparagement, distort,
   efface, eyesore, faintness, feebleness, film, filminess, fleck,
   flick, flyspeck, fog, fog up, fogginess, fuzz, fuzziness,
   half-visibility, haze, haziness, hide, imputation, indefiniteness,
   indistinctness, indistinguishability, jumble, jumble together,
   lose resolution, low profile, macula, maculation, macule, mark,
   mark of Cain, mask, mess up, mist, mistiness, mix, muddle, muddy,
   obfuscate, obscure, obscurity, odium, onus, overlook distinctions,
   pale, paleness, patch, pillorying, point champain, reflection,
   reprimand, reproach, scorch, sear, semivisibility, shadowiness,
   singe, slubber, slur, smear, smirch, smoke, smouch, smudge, smut,
   smutch, soft focus, soften, soil, spatter, speck, speckle, splash,
   splatter, splotch, spot, stain, stigma, stigmatism, stigmatization,
   stigmatize, taint, tar, tarnish, tumble, uncertainty, unclearness,
   unform, unplainness, unshape, vague appearance, vagueness, veil,
   weaken, weakness