81 entries under unbelievable topic. ×

29
improbable(adjective, slight, extraordinary, strange, superb)
18
implausible(adjective, slight, extraordinary, strange, superb)
16
doubtful(adjective, slight, uncertain, shaky, dubious)
13
incredible(adjective, extraordinary, strange, superb, fantastic)
11
dubious(adjective, open, slight, uncertain, doubtful)
10
far-fetched(adjective, hard, strange, uncertain, fantastic)
9
questionable(adjective, open, uncertain, doubtful, shaky)
8
fishy(adjective, uncertain, doubtful, shaky, dubious)
7
fantastic(adjective, extraordinary, strange, superb, amazing)
7
farfetched(adjective, improbable, unbelieveable)
6
absurd(adjective, strange, crazy, unreasonable, fantastic)
6
preposterous(adjective, obscure, strange, exceptional, crazy)
5
impossible(adjective, extraordinary, unusual, strange, unreasonable)
5
suspect(adjective, open, obscure, uncertain, doubtful)
4
extraordinary(adjective, light, thin, strange, rare)
3
flimsy(adjective, light, thin, exceptional, short)
3
strange(adjective, light, thin, extraordinary, superb)
3
unreasonable(adjective, unusual, ridiculous, absurd)
2
fabulous(adjective, awful, strange, superb, wonderful)
2
fanciful(adjective, strange, fantastic, doubtful, rare)
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APASmart Define. (2015). unlikely thesaurus. Retrieved September 30, 2026, from https://smartdefine.org/unlikely/thesaurus/synonyms
ChicagoSmart Define. 2015. "unlikely thesaurus" https://smartdefine.org/unlikely/thesaurus/synonyms (accessed September 30, 2026).
HarvardSmart Define 2015, unlikely thesaurus, Smart Define, viewed 30 September, 2026, <https://smartdefine.org/unlikely/thesaurus/synonyms>.
MLASmart Define. "unlikely thesaurus" 14 April 2015. Web. 30 September 2026. <https://smartdefine.org/unlikely/thesaurus/synonyms>