Equivocation
An informal fallacy resulting from the use of a particular word/expression in multiple senses throughout an argument leading to a false conclusion.
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Origin
Aristotle first systematically catalogued equivocation as a fallacy in Sophistical Refutations (c. 350 BCE), identifying it as one of six fallacies that arise from ambiguities in language. The term derives from the Latin aequivocus (aequus "equal" + vox "voice"), meaning "of identical sound." Abbott and Costello's classic 1938 routine "Who's on First?" remains the most beloved comic demonstration of the fallacy in action.
Updated February 22, 2026