un·knot 
(ŭn-nŏt)
(ŭn-nŏt)tr.v. un·knit or un·knot·ted, un·knot·ting, un·knots
To untie or undo (a knot).
n. (ŭnnŏt′)
In knot theory, a knot that can be unraveled in three-dimensional space into an untangled loop without cutting it or intersecting it with itself.