One who curses; a person who utters curses or calls down evil upon others.
From 'curse' plus the agent suffix '-er,' which creates nouns meaning 'one who does [verb]' (like 'teach' → 'teacher'). This formation is straightforward and has been used since Middle English.
In medieval times, a 'curser' could be a serious insult—it implied not just someone with a bad mouth, but someone with actual power to harm through dark magic or divine displeasure.
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