In the science of waves, a node is a point of minimum displacement (zero amplitude) on a standing wave, such as the stationary points on a vibrating string. See also
In celestial mechanics, a node is either of the points on the celestial sphere at which the plane of an orbit intersects a reference plane. The position of a node is one of the standard orbital elements used to specify the orientation of an orbit. An antinode lies 90° of orbital longitude away from its corresponding node. See ascending node and descending node.
In analytical geometry, a point of intersection of two or more parts of a single curve.