1. a second identity or aspect of a person that exists metaphorically as his or her substitute or representative, with different characteristics. For example, an avatar is a digital alter ego that provides a virtual representation of a computer or Internet user in games, online discussion boards, or alternate online universes.

2. an intimate, supportive friend with whom an individual can share all types of problems and experiences, as if he or she were another self.

3. in psychodrama, a group member, other than the therapist, who assumes the role of a significant figure in the protagonist’s life (see auxiliary ego) but who also speaks as part of the protagonist in order to give voice to and portray actions felt but not expressed by the protagonist.