A knot can be defined as a non-self-intersecting broken line whose endpoints coincide: when such a knot is constrained to lie in a plane, then it is simply a polygon.
A knot in its original sense can be modeled as a mathematical knot (or link) as follows: if the knot is made with a single piece of rope, then abstract the shape of that rope and then extend the working end to merge it with the standing end, yielding a mathematical knot. If the knot is attached to a metal ring, then that metal ring can be modeled as a trivial knot and the pair of knots become a link. If more than one mathematical knot (or link) can be thus obtained, then the simplest one (avoiding detours) is probably the one which one would want.
A difficult situation.
I got into a knot when I inadvertently insulted a policeman.
A man shall be perplexed with knots, and problems of business, and contrary affairs.
As they sat together in small, separate knots, they discussed doctrinal and metaphysical points of belief.
1968, Bryce Walton, Harpoon Gunner, Thomas Y. Crowell Company, NY, (1968), page 20,
He pushed through knots of whalemen grouped with their families and friends, and surrounded by piles of luggage.
A bond of union; a connection; a tie.
with nuptial knot
ere we knit the knot that can never be loosed
(nautical) A unit of speed, equal to one nautical mile per hour. (From the practice of counting the number of knots in the log-line (as it plays out) in a standard time. Traditionally spaced at one every 1/120th of a mile.)
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