52 entries under implausible topic. ×

27
flimsy(adjective, strong, light, weak, great)
23
weak(adjective, dull, strong, light, great)
19
thin(adjective, dull, light, weak, great)
17
unbelievable(adjective, extraordinary, strange, unreasonable, fantasy)
7
fanciful(adjective, light, gentle, strange, fantasy)
7
incredible(adjective, extraordinary, strange, unreasonable, fantasy)
7
unconvincing(adjective, thin, extraordinary, strange, unreasonable)
5
improbable(adjective, thin, extraordinary, strange, unreasonable)
5
inconceivable(adjective, thin, extraordinary, belief, unreasonable)
3
rare(adjective, fine, thin, extraordinary, strange)
2
absurd(adjective, irrational, unbelievable, improbable)
2
doubtful(extraordinary, unreasonable, amazing, dubious, unlikely)
2
dubious(extraordinary, unreasonable, amazing, doubtful, unlikely)
2
preposterous(adjective, extraordinary, amazing, irrational)
2
strange(adjective, extraordinary, fantasy, unreal, unbelievable)
2
uncertain(adjective, feeble, doubtful, hesitant, sluggish)
2
unconceivable(adjective, likely)
1
beyond belief(expression, extraordinary, amazing, incredible)
1
far-fetched(extraordinary, amazing, doubtful, unlikely)
1
fishy(adjective, weak, great, delicate, extraordinary)
<123>
10 years ago|15k views|share |citing 
APASmart Define. (2016). unsubstantial thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/unsubstantial/thesaurus/synonyms
ChicagoSmart Define. 2016. "unsubstantial thesaurus" https://smartdefine.org/unsubstantial/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, unsubstantial thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/unsubstantial/thesaurus/synonyms>.
MLASmart Define. "unsubstantial thesaurus" 30 March 2016. Web. 23 September 2026. <https://smartdefine.org/unsubstantial/thesaurus/synonyms>