One who annuls; a person or thing that cancels, voids, or makes something null.
From 'annul' (from Latin 'ad-' + 'nullus' meaning to make null/void) plus '-er' (one who does the action).
In law, an 'annuller' might be a judge who cancels a contract, but you'll rarely hear this word—lawyers prefer 'annulment' (the process) or 'annuls' (the verb).
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