Synonyms for Won't wash:

• adj.

  •implausible (adjective)
  • fishy,
  • suspect,
  • unsubstantial,
  • dubious,
  • farfetched,
  • puzzling,
  • impossible,
  • unconvincing,
  • problematic,
  • thin,
  • improbable,
  • flimsy,
  • weak,
  • obscure,
  • doubtful,
  • unreasonable,
  • far out,
  • too much.
  •inconceivable (adjective)
  • extraordinary,
  • rare,
  • unthinkable,
  • unimaginable,
  • mind-boggling,
  • strange,
  • phony,
  • unlikely,
  • fantastic.
  •suspicious (adjective)
  • disputable,
  • funny,
  • irregular,
  • open,
  • questionable,
  • reaching,
  • queer,
  • debatable,
  • overt,
  • shady,
  • different,
  • uncommon,
  • uncertain,
  • peculiar,
  • shaky,
  • equivocal,
  • borderline,
  • unusual,
  • unsure.
  •unbelievable (adjective)
  • flaky,
  • beyond belief,
  • thick,
  • outlandish,
  • kooky,
  • far-fetched,
  • preposterous,
  • cockamamie,
  • cockeyed,
  • astonishing,
  • harebrained,
  • lamebrained,
  • past belief,
  • screwy,
  • scatterbrained.
  •unconceivable (adjective)
  • un conceivable,
  • un-conceivable.

• Other synonyms:

  •adj.
  • incredible,
  • staggering,
  • unheard-of,
  • Unconceivable,
  • full of holes,
  • imcomprehensible,
  • implausible,
  • inconceivable,
  • suspicious,
  • unbelievable,
  • unknowable,
  • Doubtable,
  • Incogitable,
  • Insupposable,
  • open to doubt,
  • open to question,
  • out of line,
  • extra ordinary,
  • unheard of,
  • for the birds,
  • not kosher,
  • reachy,
  • rings untrue,
  • won't fly,
  • won't hold water.

Antonyms for Won't wash:

• adj.

  • implausible
    credible, possible, plausible, likely, realistic, possibly, probably, believable, reasonable, convincing, tenable.
  • inconceivable
    common, usual, normal, fathomable, imaginable, conceivable, Familiar.
  • suspicious
    definite, sure, innocent, secure, palpable, certain, trusty, Indubious, unquestionable, clear, undoubted, trustworthy.
  • unbelievable
    real.