Relating to or of the nature of a node.
Fr.: ligne des noeuds
The line connecting the ascending and descending nodes of an orbit.
Fr.: point nodal
Any of the two points on the → axis of a → lens system, such that if the → incident ray passes through one, travelling in a given direction, the → emergent ray passes the other in a parallel direction.
Fr.: regression nodale
For a ring inclined to the planet's equator, the points at which the ring crosses the equator (nodes) slowly move around the planet (regress) in a direction opposite to that of the ring's orbital motion. (Ellis et al., 2007, Planetary Ring Systems, Springer).
→ nodal; → regression.