3
unanticipated(great, excellent, superb, super, groovy)
3
unattainable(adjective, possible, impossible)
3
unexpected(great, excellent, superb, super, groovy)
3
unforeseen(great, excellent, superb, super, groovy)
3
unpredicted(great, excellent, superb, super, groovy)
3
unrealizable(adjective, possible, impossible)
3
unreasonable(adjective, unusual, incredible, impossibility)
3
unusual(adjective, light, excellent, thin, exceptional)
3
welcome(great, excellent, superb, super, groovy)
3
winning(great, excellent, superb, super, groovy)
2
beyond the pale(expression, idiom, offensive, permitted, prohibition)
2
contrary to reason(expression, idiom, impossibility)
2
extreme(adjective, unusual, special, immoral, shocking)
2
forbidden(offensive, permitted, prohibited, unmentionable)
2
foul
2
illegal(offensive, permitted, prohibition, prohibited, unmentionable)
2
impractical(adjective, possible)
2
incogitable(adjective, extraordinary, unusual, strange, amazing)
2
laughable
2
not possible(expression, idiom, impossibility)
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APASmart Define. (2015). unthinkable thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/unthinkable/thesaurus/synonyms
ChicagoSmart Define. 2015. "unthinkable thesaurus" https://smartdefine.org/unthinkable/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2015, unthinkable thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/unthinkable/thesaurus/synonyms>.
MLASmart Define. "unthinkable thesaurus" 14 April 2015. Web. 25 September 2026. <https://smartdefine.org/unthinkable/thesaurus/synonyms>