From the Latin for "I" and similar to the Greek Εγώ.
Ego = Perception of Separation from God
In spiritual psychology, the term ego refers to structures in the mind that trap the consciousness (soul, Psyche, buddha nature, jiva, nephesh etc.).
Our egoic "sense of self" is fleeting, subject to forces we do not and cannot control, and ultimately always leads to suffering. Thus, the wise person seeks to find a stable, reliable, beneficial foundation in their psyche, which is the free, unmodified consciousness.
The ego is a multiplicity of contradictory psychological elements that we have inside, and are in their sum the "ego." Each one is also called "an ego" or an "I." Every ego is a psychological defect that produces suffering. The ego is often symbolized as:
• three: such as in the three Furies, or the three traitors relate to our Three Brains or three centers of psychological processing. The first is the Demon of Desire (Astral Body), the second is the Demon of the Mind (Mental Body) and the third is the Demon of Evil Will (Causal Body).
• seven: as in the seven capital sins: laziness (sloth), lust, pride, anger (hate), envy, greed (avarice), gluttony
• legion: in their infinite combinations, such as the serpents on Medusa's head, the many heads of the Hydra killed by Heracles, or the "legion" that afflicted the suffering man in the wilderness of the Christian Gospels
Our re-union with the Divine is achieved through the death of the ego, that which causes the division. With this concept as a foundation, one can understand the symbolic martyrdom of the saints, the descent into the underworld, the battles with the dragons or monsters (symbols of the animalistic ego), etc. Through this psychological death, the consciousness (or soul; i.e. Beatrice, Persephone, Helen, Sita, etc.) is freed from its cage, and liberation from suffering is achieved.