THESAURUS
unthinkable
a bit thick, a bit thin, absurd, barred, beyond belief, closed-out, contrary to reason, doubtable, doubtful, dubious, dubitable, excluded, extraordinary, hard of belief, hard to believe, hopeless, illogical, implausible, impossible, improbable, incomprehensible, inconceivable, incredible, laughable, logically impossible, ludicrous, mind-blowing, mind-boggling, not deserving belief, not possible, open to doubt, open to suspicion, oxymoronic, paradoxical, passing belief, preposterous, problematic, prohibited, questionable, rare, ridiculous, ruled-out, self-contradictory, singular, staggering belief, suspect, suspicious, tall, thick, thin, unacceptable, unbelievable, uncommon, unconvincing, unearthly, ungodly, unimaginable, unique, unlikely, unordinary, unusual, unwonted, unworthy of belief
ROGET THESAURUS
unthinkable
Prohibition
N
prohibition, inhibition, veto, disallowance, interdict, interdiction, injunction, estoppel, embargo, ban, taboo, proscription, index expurgatorius, restriction, hindrance, forbidden fruit, Maine law, prohibitive, prohibitory, proscriptive, restrictive, exclusive, forbidding, prohibited, not permitted, unlicensed, contraband, impermissible, under the ban of, illegal, unauthorized, not to be thought of, uncountenanced,
unthinkable, beyond the pale, on no account, Int, forbid it heaven!, hands off!, keep off!, hold!, stop!, desist!, cease and desist!, avast!, that will never do, don't you dare, forget it, don't even think about doing it, go ahead, make my day.
Impossibility
N
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.