|—n , pl apsides|
|1.||Also called: apse either of two points lying at the extremities of an eccentric orbit of a planet, satellite, etc, such as the aphelion and perihelion of a planet or the apogee and perigee of the moon. The line of apsides connects two such points and is the principal axis of the orbit|
|2.||another name for apse|
|[C17: via Latin from Greek; see |
Plural apsides (āp'sĭ-dēz')
In the path of an orbiting body, either of the two points at which it is closest to or farthest away from the body it is orbiting. See also apoapsis, periapsis.