1. the nonconscious mental process by which the characteristics, beliefs, feelings, or attitudes of other individuals or groups are assimilated into the self and adopted as one’s own.

2. in psychoanalytic theory, the process of incorporating an object relationship inside the psyche, which reproduces the external relationship as an intrapsychic phenomenon. For example, through internalization the relationship between father and child is reproduced in the relationship between superego and ego or, in relational theory, between self and other. Internalization is often mistakenly used as a synonym for introjection. —internalize vb.