The Collaborative International Dictionary of English v.0.48:

Indistinct \In`dis*tinct"\ ([i^]n`d[i^]s*t[i^][ng]kt"), a. [L.
   indistinctus: cf. F. indistinct. See In- not, and
   Distinct.]
   [1913 Webster]
   1. Not distinct or distinguishable; not separate in such a
      manner as to be perceptible by itself; as, the indistinct
      parts of a substance. "Indistinct as water is in water."
      --Shak.
      [1913 Webster]

   2. Obscure to the mind or senses; not clear; not definite;
      confused; imperfect; faint; as, indistinct vision; an
      indistinct sound; an indistinct idea or recollection.
      [1913 Webster]

            When we come to parts too small four our senses, our
            ideas of these little bodies become obscure and
            indistinct.                           --I. Watts.
      [1913 Webster]

            Their views, indeed, are indistinct and dim.
                                                  --Cowper.

   Syn: Undefined; indistinguishable; obscure; indefinite;
        vague; ambiguous; uncertain; confused.
        [1913 Webster]

WordNet (r) 3.0 (2006):

indistinct
    adj 1: not clearly defined or easy to perceive or understand;
           "indistinct shapes in the gloom"; "an indistinct memory";
           "only indistinct notions of what to do" [ant: distinct]