1
tenuous
1
unanticipated
1
unbelievable(doubtful, unlikely, implausible)
1
uncertain(doubtful, unlikely, implausible)
1
unconvincing(doubtful, unlikely, implausible)
1
unforeseen
1
unfrequent
1
unimaginable(light, thin, special, doubtful, rare)
1
uninvestigated
1
unlikely(adjective, light, thin, doubtful, rare)
1
unsubstantial(doubtful, unlikely, implausible)
1
unthinkable(light, thin, extraordinary, unusual, strange)
1
unusual(light, thin, extraordinary, exceptional, special)
1
unwonted(light, thin, extraordinary, unusual, strange)
1
weak(doubtful, unlikely, implausible)
0
QT(isolated, reclusive, uncompanionable)
0
X(strange, indefinite, unidentified)
0
aberrant(unusual, special, odd, rare, bizarre)
0
abnormal(unusual, special, odd, rare, bizarre)
0
adulterated
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APASmart Define. (2013). unheard of thesaurus. Retrieved September 29, 2026, from https://smartdefine.org/unheard_of/thesaurus/synonyms
ChicagoSmart Define. 2013. "unheard of thesaurus" https://smartdefine.org/unheard_of/thesaurus/synonyms (accessed September 29, 2026).
HarvardSmart Define 2013, unheard of thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/unheard_of/thesaurus/synonyms>.
MLASmart Define. "unheard of thesaurus" 19 May 2013. Web. 29 September 2026. <https://smartdefine.org/unheard_of/thesaurus/synonyms>