The Collaborative International Dictionary of English v.0.48:
Unknot \Un*knot"\, v. t. [1st un- + knot.] To free from knots; to untie. [1913 Webster]WordNet (r) 3.0 (2006):
unknot 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]