1. a mistaken belief, especially one based on unsound arguments: "the notion that the camera never lies is a fallacy"
▪ a failure in reasoning which renders an argument invalid: "Kraft exposes three fallacies in this approach"
▪ faulty reasoning:"the potential for fallacy which lies behind the notion of self-esteem"
Word Originlate 15th century (in the sense ‘deception, guile’; gradually superseding Middle English fallace): from Latin fallacia, from fallax, fallac- ‘deceiving’, from fallere ‘deceive’.