Node

n.
  1. A knot, a knob; a protuberance; a swelling.
  2. (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.
  3. (Anat.) A small mass of tissue differing from other tissue in its immediate vicinity; as, a lymph node.
    4. Ascending node (Astron.),
    the node at which the body is passing northerly, marked with the symbol &ascendnode_;, called the Dragon's head. Called also northern node.
    Descending node ,
    the node at which the body is moving southwardly, marked thus &descendnode_;, called Dragon's tail.
    Line of nodes ,
    a straight line joining the two nodes of an orbit.