distasteful, doubtable, doubtful, dubious, dubitable, hardly possible, implausible, improbable, inappropriate, inauspicious, inconceivable, incredible, more than doubtful, objectionable, questionable, remote, unacceptable, unattractive, unbecoming, uncongenial, unfit, unfitting, unimaginable, unpromising, unpropitious, unseemly, unsuitable, unthinkable
impossibility, what cannot, what can never be, sour grapes, hopelessness, impossible, not possible, absurd, contrary to reason, unlikely
, unreasonable, incredible, beyond the bounds of reason, beyond the bounds of possibility, beyond the realm of possibility, from which reason recoils, visionary, inconceivable, prodigious, unimaginable, inimaginable, unthinkable, impracticable unachievable, unfeasible, infeasible, insuperable, unsurmountable, insurmountable, unattainable, unobtainable, out of reach, out of the question, not to be had, not to be thought of, beyond control, desperate, incompatible, inaccessible, uncomeatable, impassable, impervious, innavigable, inextricable, self- contradictory, out of one's power, beyond one's power, beyond one's depth, beyond one's reach, beyond one's grasp, too much for, ultra crepidam, the grapes are sour, non possumus, non nostrum tantas componere lites, look for a needle in a haystack, chercher une aiguille dans une botte de foin, il a le mer +a boire.
improbability, unlikelihood, unfavorable chance, bad chance, ghost of a chance, little chance, small chance, poor chance, scarcely any chance, no chance, bare possibility, long odds, incredibility, improbable, unlikely
, contrary to all reasonable expectation, wild, far out, out of sight, outtasight, heavy, rare, unheard of, inconceivable, unimaginable, inimaginable, incredible, more than doubtful, strange, bizarre (uncomformable), the chances are against, aquila non capit muscas, pedir peras pal olmo.