In a general sense the term 'separating' is applied to any planet moving away from the conjunction or aspect of another. In strict terminology, a planet is said to be 'separating' from another when the planets are within orb of aspect and moving away from perfection (exactness).

Planetary motion must be considered, for if a planet is retrograde an aspect that appears to be separating from exactness may in fact be applying, and if a planet is about to turn retrograde an aspect that is currently in a state of separation may once again perfect.