The story
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: The measure or degree to which a knot is complicated, i.e., a knot's complexity; the number of times that it is necessary to pass one part of the curve of the knot projected upon a plane through another in order to untie the knot. Full definition →
Etymology from Wiktionary, CC BY-SA 4.0.