unbelievable

• "at incredible speed"
• "the book's plot is simply incredible"

Synonyms

• incrediblebeyond belief or understanding

Synonyms

• improbablenot likely to be true or to occur or to have occurred; having a probability too low to inspire belief ; too improbable to admit of belief
• unconvincingnot convincing; having a probability too low to inspire belief
• unlikelynot likely to be true or to occur or to have occurred; has little chance of being the case or coming about; having a probability too low to inspire belief