A term used to describe the identification of consciousness with an unconscious content or complex. The most common forms of possession are by the shadow and the contrasexual complexes, anima/animus.
A man who is possessed by his shadow is always standing in his own light and falling into his own traps. Whenever possible, he prefers to make an unfavorable impression on others. . . .
Possession caused by the anima or animus presents a different picture. . . .
In the state of possession both figures lose their charm and their values; they retain them only when they are turned away from the world, in the introverted state, when they serve as bridges to the unconscious. Turned towards the world, the anima is fickle, capricious, moody, uncontrolled and emotional, sometimes gifted with daemonic intuitions, ruthless, malicious, untruthful, bitchy, double-faced, and mystical. The animus is obstinate, harping on principles, laying down the law, dogmatic, world-reforming, theoretic, word-mongering, argumentative, and domineering. Both alike have bad taste: the anima surrounds herself with inferior people, and the animus lets himself be taken in by second-rate thinking.["Concerning Rebirth," CW 9i, pars. 222f.]