The Collaborative International Dictionary of English v.0.48:

Ravel \Rav"el\ (r[a^]v"'l), v. t. [imp. & p. p. Raveled (-'ld)
   or Ravelled; p. pr. & vb. n. Raveling or Ravelling.]
   [OD. ravelen, D. rafelen, akin to LG. rebeln, rebbeln,
   reffeln.]
   1. To separate or undo the texture of; to unravel; to take
      apart; to untwist; to unweave or unknit; -- often followed
      by out; as, to ravel a twist; to ravel out a stocking.
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            Sleep, that knits up the raveled sleave of care.
                                                  --Shak.
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   2. To undo the intricacies of; to disentangle.
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   3. To pull apart, as the threads of a texture, and let them
      fall into a tangled mass; hence, to entangle; to make
      intricate; to involve.
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            What glory's due to him that could divide
            Such raveled interests? has the knot untied?
                                                  --Waller.
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            The faith of very many men seems a duty so weak and
            indifferent, is so often untwisted by violence, or
            raveled and entangled in weak discourses! --Jer.
                                                  Taylor.
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WordNet (r) 3.0 (2006):

ravelling
    n 1: a bit of fiber that has become separated from woven fabric
         [syn: raveling, ravelling]