Oriental and occidental
A planet is oriental when it rises before the Sun and occidental when it sets after it, a distinction classical astrology reads as a difference in how the planet acts.
Oriental means eastern of the Sun, appearing in the morning sky ahead of it; occidental means western, following it into the evening. Only Mercury and Venus alternate quickly, which is why the terms come up most often for them.
The traditional reading is temperamental rather than evaluative: an oriental planet acts openly and early, an occidental one later and more reflectively. Some authors tie the preference to sect, giving the diurnal planets a preference for one side and the nocturnal for the other.
Frequently asked
How do I tell whether a planet is oriental?
Compare its longitude with the Sun's: a planet at an earlier degree rises before the Sun and is oriental.
Which planets does it matter most for?
Mercury and Venus, because they are never far from the Sun and change sides often enough for it to describe something.