1.A knot, a knob; a protuberance; a swelling.
3.(Math., Computers) A special point in a graph or diagram which is attached to other points by links. It is often labeled and represented graphically as a box or circle. A node may represent any object which is related to other objects in a conceptual structure that can be represented as a graph, the relations being represented as links between the nodes.
4.(Anat.) A small mass of tissue differing from other tissue in its immediate vicinity; as, a lymph node.