Definition of knot:
(n) :
a
looping of a piece of string or of any other long, flexible material that cannot be untangled without passing one or both ends of the material through its loops; (of hair, etc) A
tangled
clump
"when climbing, it is important to make sure that your knots are both secure and of types that will not weaken the rope."
"she knotted the ends of the rope to keep it from unravelling."