4
meaningless(adjective, false, unreasonable, unimportant, trivial)
4
otherworldly(adjective, excellent, gentle, strange, marvelous)
4
phantasmal
4
precarious
4
rarefied(adjective, fine, thin, delicate, slim)
4
thick(adjective, thin, extraordinary, unreasonable, amazing)
4
unrealistic(adjective, unreal)
4
unreliable(false, ill, insane, unhealthy, frail)
4
worthless(adjective, weak, feeble, useless, trivial)
4
wraithlike(adjective, heavenly, ghostly, incorporeal, nonmaterial)
3
abstract(adjective, fantastic, unreal, insubstantial, theoretical)
3
brittle(adjective, weak, delicate, feeble, infirm)
3
delusionary
3
evanescent
3
fancied(adjective, strange, fantasy, unreal)
3
fantastical(adjective, strange, fantasy, unreal)
3
fine
3
frivolous(weak, soft, gentle, content)
3
groundless(error, unsubstantiality)
3
inconsiderable(adjective, weak, soft, gentle, mild)
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APASmart Define. (2016). unsubstantial thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/unsubstantial/thesaurus/synonyms
ChicagoSmart Define. 2016. "unsubstantial thesaurus" https://smartdefine.org/unsubstantial/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2016, unsubstantial thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/unsubstantial/thesaurus/synonyms>.
MLASmart Define. "unsubstantial thesaurus" 30 March 2016. Web. 25 September 2026. <https://smartdefine.org/unsubstantial/thesaurus/synonyms>