What's a knot? 

Etymology

A ridiculous spelling of the word “not.” As in, “That’s not coming undone.” Shortened some time after the pleistocene epoch to “that’s not,” then by italians to “that’s a not,” and later altered by an imbicile to start with “k”. 

Definition

knot  noun  Twisted, tangled code.  Generally code is “knotted” when it’s difficult to untangle. (2) A code pattern with bends in the control flow crossing earlier bends.