The Collaborative International Dictionary of English v.0.48:

Indistinctly \In`dis*tinct"ly\ ([i^]n`d[i^]s*t[i^][ng]kt"l[y^]),
   adv.
   In an indistinct manner; not clearly; confusedly; dimly; as,
   certain ideas are indistinctly comprehended.
   [1913 Webster]

         In its sides it was bounded distinctly, but on its ends
         confusedly and indistinctly.             --Sir I.
                                                  Newton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

indistinctly
    adv 1: in a dim indistinct manner; "we perceived the change only
           dimly" [syn: dimly, indistinctly]