The term 'Knotty Swelling' can be broken down into two crossword solutions: NODE (4 letters). A NODE is a point in a network or system where lines or pathways intersect or branch. In biology, a NODE is a swelling or enlargement of tissue. Knotty Swelling is a term used to describe a type of medical condition where a knot-like lump appears on the body and swells up. This condition is usually caused by an infection or inflammation.