Third person singular or plural of 'empoison': to poison or contaminate something, or to make something harmful or malicious.
From Middle English and Old French 'empoisoner'. The verb form adds the standard '-s' ending for third person singular present tense or plural forms.
This is one of those archaic verbs that Shakespeare loved—it means not just to literally poison food, but to poison relationships, reputations, and atmospheres with malice and deception.
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