6
unimaginable(adjective, light, extraordinary, strange, rare)
5
impossible(adjective, extraordinary, unusual, strange, unreasonable)
5
indefinite(shaky, ambiguous, unpromising)
5
moot(uncertain, doubtful, unsure, ambiguous, debatable)
5
indistinct(shaky, ambiguous, unpromising)
5
ridiculous(adjective, strange, crazy, doubtful, dubious)
5
slender(adjective, slight, remote)
5
suspect(adjective, open, obscure, uncertain, doubtful)
5
unacceptable(adjective, inappropriate, unsuitable, unsuited, inapt)
5
unpromising(adjective, inadequate, useless, shaky, inappropriate)
4
equivocal(uncertain, doubtful, unsure, ambiguous)
4
borderline(shaky, ambiguous, unpromising)
4
doubtable(adjective, open, obscure, uncertain, doubtful)
4
dubitable(adjective, uncertain, doubtful, shaky, unsure)
4
extraordinary(adjective, light, thin, strange, rare)
4
faint(adjective, slight, doubtful, remote, dubious)
4
improbably(adverb, improbably)
4
inappropriate(adjective, inadequate, useless, unhealthy, unsuitable)
4
unbecoming(adjective, inadequate, useless, inappropriate, unhealthy)
4
unclear(adjective, uncertain, doubtful, shaky, dubious)
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APASmart Define. (2015). unlikely thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/unlikely/thesaurus/synonyms
ChicagoSmart Define. 2015. "unlikely thesaurus" https://smartdefine.org/unlikely/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2015, unlikely thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/unlikely/thesaurus/synonyms>.
MLASmart Define. "unlikely thesaurus" 14 April 2015. Web. 24 September 2026. <https://smartdefine.org/unlikely/thesaurus/synonyms>