adjective

unlikely and unconvincing; implausible.

the theory sounded bizarre and far-fetched

improbable,unlikely,implausible,scarcely credible,difficult to believe,dubious,doubtful,unconvincing,incredible,unbelievable,unthinkable,contrived,strained,laboured,forced,elaborate,overdone,fanciful,unrealistic,ridiculous,absurd,preposterous,hard to swallow/take,fishy,hokey