4
unsafe(adjective, dishonest, deceitful, unreliable, insecure)
4
unsound(adjective, uncertain, unsettled, dubious, unpredictable)
4
unstable(adjective, open, obscure, uncertain, unsettled)
4
unthinkable(adjective, extraordinary, amazing, unbelievable, implausible)
4
weak(adjective, great, extraordinary, amazing, doubtful)
3
apocryphal
3
changeable(adjective, uncertain, doubtful, vague, hesitant)
3
clouded(adjective, clear, certain, uncertain, doubtful)
3
contentious(adjective, doubtful, dubious, provocative, debatable)
3
cryptic(adjective, uncertain, doubtful, vague, dubious)
3
dicey(adjective, shaky, unlikely, unpromising)
3
difficult(adjective, tricky, sticky, challenging)
3
discreditable(adjective, disrepute)
3
dishonourable
3
dodgy(adjective, corrupt, dishonest, dubious, suspect)
3
enigmatic(adjective, uncertain, doubtful, vague, dubious)
3
evasive
3
fantastic(adjective, unlikely, unbelievable, improbable)
3
funny(unusual, strange, dubious, suspect, shady)
3
hard to believe(expression, adjective, idiom, unbelief doubt)
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APASmart Define. (2015). questionable thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/questionable/thesaurus/synonyms
ChicagoSmart Define. 2015. "questionable thesaurus" https://smartdefine.org/questionable/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2015, questionable thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/questionable/thesaurus/synonyms>.
MLASmart Define. "questionable thesaurus" 13 April 2015. Web. 20 September 2026. <https://smartdefine.org/questionable/thesaurus/synonyms>