The Collaborative International Dictionary of English v.0.48:

Unravel \Un*rav"el\, v. t. [1st pref. un- (intensive) + ravel.]
   [1913 Webster]
   1. To disentangle; to disengage or separate the threads of;
      as, to unravel a stocking.
      [1913 Webster]

   2. Hence, to clear from complication or difficulty; to
      unfold; to solve; as, to unravel a plot.
      [1913 Webster]

   3. To separate the connected or united parts of; to throw
      into disorder; to confuse. "Art shall be conjured for it,
      and nature all unraveled." --Dryden.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Unravel \Un*rav"el\, v. i.
   To become unraveled, in any sense.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unravel
    v 1: become or cause to become undone by separating the fibers
         or threads of; "unravel the thread" [syn: unravel,
         unknot, unscramble, untangle, unpick] [ant: knot,
         ravel, tangle]
    2: disentangle; "can you unravel the mystery?" [syn: ravel,
       unravel, ravel out] [ant: knot, ravel, tangle]
    3: become undone; "the sweater unraveled" [syn: run,
       unravel]