/ ˈfæləsi; NAmE / noun ( pl. -ies )
1.
[ C ] a false idea that many people believe is true :
It is a fallacy to say that the camera never lies.
2.
[ U , C ] a false way of thinking about sth :
He detected the fallacy of her argument.
—see also pathetic fallacy
••
WORD ORIGIN
late 15th cent. (in the sense deception, guile ; gradually superseding Middle English fallace ): from Latin fallacia , from fallax , fallac- deceiving, from fallere deceive.