The conscious and permanent subject of all psychical experiences, whether held to be directly known or the product of reflective thought; the subject consciously considered as "I" by a person; -- opposed to non-ego.

that one of the three parts of a person's psychic apparatus that mediates consciously between the drives of the id and the realities of the external physical and social environment, by integrating perceptions of the external world and organizing the reactions to it. Contrasted with the id and superego.

self-esteem; as, he has an overinflated ego.

In Freudian theory, an aspect of personality that develops during infancy and operates on the reality principle, seeking acceptable means of gratification in dealing with the real world.