Litteraly means "Hidden" in Latin.
The study of the unknown and unseen, what may be described as "Metaphysical" or Esoteric (as opposed to Exoteric).
Is certainly NOT limited to Satanism or Wicca, infact many practicing Occultists are CHRISTIANS, or Gnostics moreover.
Occultists seek the "Light in the Darkness" and the Cause of causes; what is REALLY happening as opposed to what you are told is happening, and to see the world without perspective (Gnosis).
Wrongly persecuted by Christianity and the masses for falsey based assumptions and superstitions.
The Christian Qabalah. Occult orders such as the O.T.O. or the Golden Dawn