1. (a.) Not credulous; indisposed to admit or accept that which is related as true, skeptical; unbelieving\.

2. (a.) Indicating, or caused by, disbelief or incredulity.

3. (a.) Incredible; not easy to be believed.

Humean Pyrrhonic agnostic cautious creedless disbelieving disinclined to believe disposed to doubt distrustful doubtful doubting dubious faithless guarded hard of belief heretical hesitant impervious to persuasion inconvincible irreligious leery minimifidian mistrustful nonbelieving nullifidian questioning quizzical repudiative sceptical shy of belief skeptic skeptical suspecting suspicious unbelieving uncertain unconfident unconverted unconvinced unconvincible uncredulous unpersuadable unpersuasible unsatisfied unwilling to accept wary without faith