Definitions for "Periapsis"
The point in an orbit closest to the body being orbited. (Related terms include perihelion, perigee, and pericrone, which are periapses in Sun, Earth, and Saturn orbits, respectively.) See also apoapsis.
The point of an orbit nearest to the center of attraction of an orbiting body.
The closest point in an orbit to the primary body. For earth orbits periapsis is known as perigee (see below).