According to Freudian psychoanalytical theory, it is a feature of personality, developing during infancy, that operates on the basis of the reality principle. One of three components of the psychic apparatus, it is a way of seeking acceptable means of gratification in dealing with the real world. Originally derived by Freud from the German word Ich, it was transmuted to ego in translation, and came into colloquial use to mean something like self-esteem.
See Anhedonia, Id, Psychoanalysis, Pleasure-pain principle, Psychodynamic theory, Reality principle, Self, Self-esteem, Superego