Definition of periapsis in English:

periapsis

noun

Astronomy
  • The point in the path of an orbiting body at which it is nearest to the body that it orbits.

    • ‘For objects orbiting Earth, periapsis and apoapsis are known as perigee and apogee; for objects orbiting the Sun, these locations are known as perihelion and aphelion.’
    • ‘At periapsis [closest approach to Saturn] it's about 40 kilometers per second [90,000 miles per hour].’

Pronunciation:

periapsis

/ˌperēˈapsis/