Orbital elements
Periapsis
Periastron
Perigee
Perihelion
Apastron
Aphelion
Apocentre
Apocenter
Apogee
Apse
Apsis
The point of greatest or least distance of the orbit of a celestial body from a center of attraction. The closest point is the periapsis, the further point the apoapsis.
Apsides