Cathexis
In our understanding, when used to define narcissism, the term
cathexis refers to the fact that one experiences one's self-concept
as inseparable from one's self. It highlights the intimate integration
of this self-concept. It becomes easier to understand if we think
of it in relation to the integration of the sense of identity.
Cathexis, then, means the integration of one's identity. We term
this integration, in our work, self-realization. In other words,
the cathexis of the self is a psychoanalytic concept that approximates
our concept of the realization of the self. (The Point of Existence,
pg 478)

Narcissism is the cathexis (libidinal investment)
of the self. (The Point of Existence)

Libidinal cathexis shifts substantially into the
service of the rapidly growing autonomous ego and its functions,
and the child seems intoxicated with his own faculties and with
the greatness of his own world. (The Pearl Beyond Price)