W: (adj) valid [Indirect via invalid] (well grounded in logic or truth or having legal force) "a valid inference"; "a valid argument"; "a valid contract"
S: (adj) deceitful, fallacious, 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"
S: (adj) fallacious (based on an incorrect or misleading notion or information) "fallacious hope"