13
marvelous(adjective, good, hard, great, excellent)
13
staggering(adjective, great, excellent, extraordinary, superb)
12
impossible(verb, adjective, hard, extraordinary, strange)
12
unlikely(adjective, obscure, extraordinary, strange, superb)
12
unsubstantial(adjective, extraordinary, strange, unreasonable, fantasy)
11
preposterous(adjective, hard, great, obscure, difficult)
11
questionable(adjective, weak, great, flat, poor)
11
remarkable(adjective, great, excellent, extraordinary, superb)
11
terrific(adjective, great, excellent, superb, wonderful)
10
doubtful(adjective, great, extraordinary, unreasonable, fantastic)
10
fanciful(adjective, great, excellent, strange, superb)
9
flimsy(adjective, weak, poor, thin, informal)
9
spectacular(adjective, great, excellent, extraordinary, superb)
9
weak(adjective, great, poor, extraordinary, strange)
8
breathtaking(adjective, great, excellent, extraordinary, superb)
8
absurd(adjective, hard, difficult, strange, marvelous)
8
appealing(great, excellent, superb, super, groovy)
8
dubious(adjective, great, extraordinary, unreasonable, amazing)
8
exceptional(adjective, obscure, extraordinary, remarkable, unknown)
8
far-fetched(adjective, hard, great, extraordinary, strange)
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APASmart Define. (2016). unbelievable thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/unbelievable/thesaurus/synonyms
ChicagoSmart Define. 2016. "unbelievable thesaurus" https://smartdefine.org/unbelievable/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2016, unbelievable thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/unbelievable/thesaurus/synonyms>.
MLASmart Define. "unbelievable thesaurus" 30 March 2016. Web. 27 September 2026. <https://smartdefine.org/unbelievable/thesaurus/synonyms>