Ego
The ego (Latin "I") is, in psychology, the part of the self that mediates between conscious experience and the world. Freud defined it as one of the three psychic structures (id, ego, superego). Jung sees the ego as center of consciousness — different from the Self, which is the totality of the psyche.
Ego in spiritualities
Eastern traditions (Buddhism, Hinduism) tend to see the ego as illusion (anatta in Buddhism). Spiritual goal: transcend the ego to access deeper consciousness.