A person who studies or has expert knowledge about demons and demonology.
From demon + -om- + -ist (one who practices). This is a less common variant formation than demonologist, appearing occasionally in older theological and occult texts.
English loves creating multiple words for the same specialist—like how we have both 'linguist' and 'philologist'—and demonomist was one way scholars tried to establish authority in demon studies before demonologist became standard.
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