Q:

LOPG/Deep Space Gateway - What is a cislunar orbit?

Formerly the Deep Space Gateway and now the Lunar Orbital Gateway or LOPG station, is planned for Expedition 1 aka the maiden launch of the SLS. After reading several specifications, to avoid the "gravity well" of earth the station will remain on a cislunar orbit. Some sources say that the station will be equipped with electric propulsion systems to adjust orbits, around the earth and the moon. 
What is a cislunar orbit, and with this sort of orbit, could the station also orbit the earth with minor burns, and how would this work for rendezvous and docking?

A:

Cislunar space is a large area:

The region outside Earth's atmosphere and extending out to just beyond the Moon's orbit, including the Lagrangian points, is sometimes referred to as cis-lunar space.

Earth orbits, Moon orbits and orbits around both (like Apollo 13's free return trajectory) can all be called cislunar orbits. 
LOP-G would use a halo orbit:

Such orbits, which make close passes by the moon and loop far out, have the advantage of being near the moon, but always keep a station within the line of sight of flight controllers on Earth, as well as in sunlight for solar arrays.

