A substance or agent that causes or produces disease in an organism.
From Greek athos (unclear origin, possibly related to 'ailment') plus -gen (Greek suffix meaning 'producer' or 'generator'). This is a technical/medical term combining medical roots.
Athogen is one of those medical words that's so technical it's almost disappeared from use—modern doctors prefer 'pathogen' instead, but athogen shows how scientists in different eras created parallel vocabulary for discussing disease.
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