A knot which tightens around an object when strained but slackens when the strain is removed. Running knots are sometimes also known as slip knots or nooses.
Running Knot
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References
Owen, P. Knots. Philadelphia, PA: Courage, p. 60, 1993.Referenced on Wolfram|Alpha
Running KnotCite this as:
Weisstein, Eric W. "Running Knot." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/RunningKnot.html