periapsis

For an object orbiting a celestial body, the periapsis' is the point in the orbit which is closest to that body.

Periapsis and apoapsis are generic terms. The prefixes "peri-" and "apo-" are commonly applied to the Greek or Roman name of the particular body being orbited.

As an example, consider perigee and apogee for Earth, perijove and apojove for Jupiter, periselene and aposelene or perilune and apolune for lunar orbit, perichron and apochron for Saturn, perihelion and apohelion for the Sun, etc.