Roget's Thesaurus of English Words and Phrases by Peter Mark Roget

4. Unsubstantiality — N. unsubstantiality†, insubstantiality;

nothingness, nihility†; no degree, no part, no quantity, no thing. nothing, naught, nil, nullity, zero, cipher, no one, nobody; never a one, ne'er a one [Contr.]; no such thing, none in the world; nothing whatever, nothing at all, nothing on earth; not a particle &c (smallness) 32; all talk, moonshine, stuff and nonsense; matter of no importance, matter of no consequence. thing of naught, man of straw, John Doe and Richard Roe, faggot voter; nominis umbra [Lat.], nonentity; flash in the pan, vox et praeterea nihil [Lat.]. shadow; phantom &c (fallacy of vision) 443; dream &c (imagination) 515; ignis fatuus &c (luminary) 423 [Lat.]; such stuff as dreams are made of [Tempest]; air, thin air, vapor; bubble &c 353; baseless fabric of a vision [Tempest]; mockery. hollowness, blank; void &c (absence) 187. inanity, fool's paradise. V. vanish, evaporate, fade, dissolve, melt away; disappear &c 449. Adj. unsubstantial; baseless, groundless; ungrounded; without foundation, having no foundation. visionary &c (imaginary) 515; immaterial &c 137; spectral &c 980; dreamy; shadowy; ethereal, airy; cloud built, cloud formed; gossamery, illusory, insubstantial, unreal. vacant, vacuous; empty &c 187; eviscerated; blank, hollow; nominal; null; inane. Phr. there's nothing in it; an ocean of dreams without a sound [Shelley].