intended to deceive; "deceitful advertising"; "fallacious testimony"; "smooth, shining, and deceitful as thin ice" - S T Coleridge; "a fraudulent scheme to escape paying taxes"
If an idea, argument, or reason is fallacious, it is wrong because it is based on a fallacy. Their main argument is fallacious. containing or based on false ideas
based on an incorrect or misleading notion or information; "fallacious hope" containing or based on a fallacy; "fallacious reasoning"; "an unsound argument