1. the infant’s emerging consciousness of being a separate individual distinct from others, particularly the parents.

2. in classical psychoanalysis, the process in which a part of the id is gradually transformed into the ego as a result of environmental demands. It involves a preconscious stage, in which the ego is partly developed, and a subsequent conscious stage, in which such ego functions as reasoning, judging, and reality testing come to fruition and help to protect the individual from internal and external threats. Also called ego formation.