The rules, laws, or systematic principles governing demons and their behavior, or the study of such laws.
From demon + -nomy (from Greek nomos meaning 'law' or 'custom'). The suffix -nomy is used in astronomy, economy, and taxonomy to mean the study of laws or organization principles.
Just like astronomy is the laws of stars and economy is the laws of household management, demonomy would theoretically be the 'laws of demons'—showing how -nomy creates an elegant parallel structure across totally different fields.
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