A narcissistic breakdown — also called narcissistic collapse — occurs when the external structures a narcissist depends on to maintain their self-image fail simultaneously or catastrophically, leaving them unable to regulate their sense of self through the usual mechanisms of control, supply, and impression management.

Narcissistic supply is the external attention, admiration, validation, or emotional reaction that a narcissist depends on to maintain their self-image and regulate their sense of worth — because they lack the internal capacity to do this without constant reinforcement from others.