Definition of unsubstantial:
vapid, delicate, nonphysical, frail, light, insubstantial, inconceivable, discarnate, profitless, likely, infirm, metaphysical, disembodied, inconstant, unsatisfying, wraithlike, deceitful, vain, delusive, fragile, unbodied, decrepit, unbelievable, airy, nugatory, unconvincing, worthless, unreal, unprofitable, baseless, unsound, weakly, weak, fragile, unimportant, thin, trifling, incredible, strong, improbable, feeble, implausible, artificial, unconceivable, aery, useless, uncorporal, ethereal, visionary, frail, body, futile, shaky, aeriform, flimsy, jejune, abortive, idle, thin, puny, fruitless, shadowy, ineffectual, unavailing, trivial, bootless, aerial, unserviceable.
- immaterial (part of speech: adjective)
- unsubstantial (part of speech: adjective)
- unreal (part of speech: adjective)
- "The Adventure of Living", John St. Loe Strachey.
- "Jess", H. Rider Haggard.
- "The Betrayal", E. Phillips Oppenheim.