Ego is a Latin word meaning "I", which in English is used to refer to:
1. In psychoanalysis, the ego is the part of the mind that mediates between the conscious and the unconscious and is responsible for reality testing and a sense of personal identity.
2. In general usage, ego refers to a person's sense of self-esteem or self-importance.
3. In philosophy, ego refers to the thinking subject or the self.
4. In Buddhism, ego refers to the illusion of a separate self.