#1 fallacious s. [unsound] containing or based on a fallacy; "fallacious reasoning"; "an unsound argument". wn
#2 fallacious s. [deceitful, fraudulent] intended to deceive; "deceitful advertising"; "fallacious testimony"; "smooth, shining, and deceitful as thin ice" - S.T.Coleridge; "a fraudulent scheme to escape paying taxes". wn
#3 fallacious s. based on an incorrect or misleading notion or information; "fallacious hope". wn
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