In a manner showing excessive and obsessive enthusiasm, especially about a cause, belief, or activity; with extreme or irrational devotion.
From 'fanatic' plus the -ally suffix. 'Fanatic' comes from Latin 'fanaticus' (divinely inspired, frenzied), derived from 'fānum' (temple), originally suggesting someone possessed by divine madness.
The Latin root 'fānum' (temple) reveals that Romans originally saw fanatics as people touched by god—what we now call mental illness or obsession, they called divine inspiration, showing how culture completely rewrites the meaning of behavior.
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