Knot1  —n. 1 a intertwining of rope, string, hair, etc., so as to fasten. B set method of this (reef knot). C knotted ribbon etc. As an ornament. D tangle in hair, knitting, etc. 2 unit of a ship's or aircraft's speed, equivalent to one nautical mile per hour. 3 (usu. Foll. By of) cluster (knot of journalists). 4 bond, esp. Of marriage. 5 hard lump of organic tissue. 6 a hard mass in a tree-trunk where a branch grows out. B round cross-grained piece in timber marking this. 7 central point in a problem etc. —v. (-tt-) 1 tie in a knot. 2 entangle. 3 unite closely.  at a rate of knots colloq. Very fast. Tie in knots colloq. Baffle or confuse completely. [old english]