narcissism

Narcissism comes from obsolete German Narzissismus (now Narzissmus, shortened by haplology), built from the name Narziss plus the suffix -ism. That name traces back to Narcissus, the figure in Greek mythology who became obsessed with his own reflection.

The facts given don't describe a documented shift in meaning — the word was formed directly by attaching -ism to the mythological name, marking a state or condition named after Narcissus's obsession.

The word is built from Narcissus plus the common suffix -ism, the same pattern seen in words like heroism or magnetism, where a name or noun becomes the label for a whole condition tied to it.