fallacious

1 not using or following good reasoning it's fallacious to say that something must exist because science hasn't proven its nonexistence Synonyms illogical, illegitimate, inconsequent, inconsequential, invalid, irrational, nonrational, unreasonable, unreasoning, unsound, weakRelated Words eristic (also eristical), misleading, sophistic (or sophistical), specious; half-baked, ill-advised, misguided, unconsidered, unreasoned; inconsistent; absurd, asinine, foolish, meaningless, nonsensical, preposterous, reasonless, senseless, silly; Kafkaesque, odd, peculiar, strange, surreal, unusual, weird; insane, mad, nutty, wacky (also whacky); disordered, disorganized, rambling, random; unconvincing; inexplicable, unaccountable, unexplainableNear Antonyms commonsense, sane, sensible, sober, wise; enlightened, informed, just, justified, reasoned; ordered, organized; clear, cogent, compelling, convincing, credible, persuasive, plausible, satisfying, solid; certain, sure, true; confirmed, corroborated, demonstrated, established, substantiated, validatedAntonyms logical, rational, reasonable, sound, valid, well-founded, well-grounded

2 tending or having power to deceive consumers who harbor the fallacious belief that credit-card spending will never catch up with them Synonyms beguiling, deceitful, deceiving, deluding, delusive, delusory, deceptive, false, misleading, speciousRelated Words artful, crafty, cunning, devious, foxy, guileful, shady, shifty, slick, sly, sneaking, sneaky, subtile, subtle, trick, trickish, tricky, underhand, underhanded, wily; inaccurate, incorrect, wrong; bewildering, confounding, distracting, perplexing, puzzling; ambidextrous, crooked, defrauding, dishonest, dissembling, double-dealing, duplicitous, faithless, fast, fraudulent, knavish, lying, mendacious, untrustworthy, untruthful; bogus, counterfeit, fake, feigned, forged, jive [slang], phony (also phoney), sham, spurious; insidious, perfidious, treacherous; ambiguous, circuitous, equivocal, evasive; artificial, backhanded, hypocritical, insincere, left-handed, two-facedNear Antonyms candid, direct, foursquare, frank, free-spoken, open, openhearted, outspoken, plain, plainspoken, straight; clarifying, elucidative, explanatory, illuminating; revealing, revelatory; honest, trustworthy, truthfulAntonyms aboveboard, forthright, nondeceptive, straightforward